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Full text of "Practical astronomy with the unaided eye"

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TACTICAL 
ASTRONOMY 

WITH THE UNAIDED EYE 



BY 






*v 



The Rev. HECTOR MACPHERSON 

M.A., F.R.A.S., F.R.S.E. 

MEMBER OF THE SOCIETE ASTRONOMIQUE DE FRANCE, ETC. 

AUTHOR OF "THE ROMANCE OF MODERN ASTRONOMY," "ASTRONOMERS 

OF TO-DAY," "A CENTURY'S PROGRESS IN ASTRONOMY" 




REVISED EDITION 




SJotrfcott attb (BMnbttr^h : 

T. C. & E. C. JACK, LTD. | T. NELSON & SONS, LTD. 
1919 



CONTENTS. 








I. Introductory 5 


II. The Northern Stars 






. 24 


III. The Stars of Winter . 






. 36 


Y. The Stars op Spring 






. 54 


V. The Stars op Summer . 






66 


VI. The Stars of Autumn . 






82 


VII. The Southern Stars 






95 


VIII. Sun, Moon, and Planets 






101 


IX. Astronomical Phenomena 






116 


Bibliography .... 






126 


Index 






127 



PRACTICAL ASTRONOMY. 



CHAPTER I. 

INTRODUCTORY. 

When we cast our eyes to the heavens on 
any clear and, by preference, moonless night, 
our attention is attracted by apparently in- 
numerable points of light, of all degrees of 
brightness. These are the stars, which in all 
ages have drawn to themselves the attention 
of mankind. Mr. E. W. Maunder, in a previ- 
ous volume of this series, has shown how man's 
attention was first directed to the heavenly 
bodies, and how the mere recognition of the 
phases of the Moon, the varying positions of the 
planets and the seasonal changes of the stars 
has developed stage by stage into the science 
of astronomy as we know it at the present day. 
Perhaps of all the sciences modern as- 
tronomy is the most awe-inspiring, the most 
wonderful, the most instructive. The aver- 
age man reads of the marvels which the 
telescope and spectroscope reveal, of the 



6 PKACTICAL ASTRONOMY. 

great depths and spaces, the rapid velocities, 
the eternal working of evolution, and he 
wonders. He has little or no knowledge of 
the methods used by the astronomers in 
ascertaining the '"acts of the science ; and 
he is not familiar with the stars or constella- 
tions. Let us suppose that there is something 
unusual in the astronomical world. The news- 
papers are full of the " opposition of Mars." 
The average man has read about Mars and he 
is anxious to see the planet for himself. The 
almanacs tell him that it is in a certain con- 
stellation, say, Virgo, and the newspapers 
repeat the statements of the almanacs. The 
would-be observer of Mars is as puzzled as 
ever. He knows nothing of the constellation 
Virgo. He does not know where to look for 
it, and even if he did, he would probably be 
unable to recognise it. He is paying the 
penalty for not having made himself ac- 
quainted with what we may call the topog- 
raphy of the heavens. 

Again, let us suppose that a bright comet 
is to be seen or that a meteoric shower is 
expected from a certain constellation, say, 
Leo. The would-be observer is in the same 
position as in the case previously mentioned. 
His ignorance of the topography of the sky is 
at the root of his inability to see the comet 
or to witness the meteoric shower. 



INTRODUCTORY. 7 

So much for the utility of knowing the 
names of the various stars and constella- 
tions ; but a knowledge of this kind is more 
than merely useful. No one can really enter 
into what may be called the spirit of astron- 
omy without having an acquaintance, how- 
ever slight, with the planets and stars in- 
dividually. As a contemporary astronomer 
has well remarked : " How great an interest 
is given to any object by the fact that we 
know its name. Take some town children 
out into the country and set them to gather 
wild flowers : how instantly they ask their 
names." It is the same in the case of the 
stars. When in a clear night we " consider 
the heavens " and behold apparently count- 
less points of light, we are confused and over- 
whelmed by the number of the stars and 
by the complexity of their distribution. One 
star appears to be almost the same as an- 
other, except for the differences in bright- 
ness, and we look away from the sky again 
with neither interest nor curiosity. But 
if we learn that such and such a star is Al- 
debaran, and such and such is Sirius, and 
such and such a constellation is Orion, then 
our interest in the stars is aroused and as a 
result we are desirous of tracing out the star 
groups and of identifying the stars themselves. 

" But," the would-be astronomer asks at 



8 PRACTICAL ASTRONOMY. 

this time, " how is it possible for me to learn 
the names of the stars and trace the outlines 
of the constellations without being taught 1 " 
Carlyle in his old age lamented " Why did 
not somebody teach me the constellations 
and make me at home in the starry heavens ? " 
But in reality it is not necessary for anyone 
to be taught the constellations. It is best 
for everyone to learn them for himself. 

When the would-be astronomer begins his 
task it may seem almost impossible of attain- 
ment, and some of the hints which are given 
in astronomical books only make the task 
more difficult. For instance, when we are 
told to draw imaginary lines through such 
and such stars in the Plough, and that these 
will lead us to such and such stars in Bootes 
and will form triangles and quadrilaterals 
with such and such stars in Draco, we feel 
baffled with the magnitude of the task. Again, 
on some maps and guides to the heavens there 
are represented what are known as " the 
constellation figures." On such maps we 
find the Plough represented by the figure of 
a bear covered with stars, Cygnus by a star- 
spangled swan, Orion by a human figure 
dotted with stars. The stars of all mag- 
nitudes are inserted and named, but they are 
confused and individually lost through the in- 
troduction of the constellation figures. These 



INTRODUCTORY. 9 

figures of course are of extreme interest to the 
historian of astronomy and to the antiquarian. 
They throw a flood of light on important 
questions connected with the beginnings of 
astronomical science, but on star maps in- 
tended for the beginner who desires to obtain 
a knowledge of the topography of the heavens, 
they are utterly out of place. 

The best method of acquiring a knowledge 
of the stars is to study them as they are, and 
to obtain a knowledge of the most important 
constellations in the heavens which it is 
impossible to mistake. From this it is com- 
paratively easy to trace out the other con- 
stellations ; to simplify this task by ex- 
planation and direction is the aim of the 
following pages. 

Once the observer has become familiar 
with the various constellations and their 
seasonal changes a new charm is added to 
his interest in the stars. As an able astron- 
omer has remarked, the task of learning the 
stars " has a charm of its own. The silent 
watchers from heaven soon become each a 
familiar friend, and to any imaginative mind 
the sense that he is treading the same path 
as that traversed by the first students of 
Nature will have a strange charm." 

Our Place in the Universe. Before enter- 
ing on the task of describing the topog- 



10 PRACTICAL ASTRONOMY. 

raphy of the heavens, it is necessary to 
consider briefly our position in the Universe 
and the bearing of the position and motions 
of our planet on the appearance of the heavens, 
and on the apparent motions of Sun, Moon, 
planets and stars. 

We live on the Earth, a globe almost 8000 
miles in diameter. This globe is not, as the 
ancient astronomers believed, suspended in 
space. It is in ceaseless motion ; it turns 
on its axis once in twenty-four hours, and in 
addition it revolves round the sun in 365J 
days. The mean distance of the Earth from 
the Sun is 93,000,000 miles, so the pathway 
traversed by our world is about 186,000,000 
miles in diameter. In order to travel round 
this great orbit in a year, the Earth whirls 
through space at the amazing rate of eighteen 
miles in one second. 

But the Earth does not travel alone. It is 
accompanied on its journey by its faithful 
satellite the Moon. The Moon revolves round 
the Earth in a little over twenty-seven days, 
at an average distance of 238,000 miles. Just 
as we get our unit of time, a day, from the 
rotation of the Earth on its axis, and a year 
from the Earth's revolution round the Sun, 
we derive our other unit, the month, from the 
Moon's revolution round the Earth. 

The Earth is not, however, the only body 



INTRODUCTORY. 11 

which revolves round the Sun. The orb of 
day holds sway over a large system of bodies 
planets, comets and meteors. The five 
larger planets are very conspicuous and have 
been known from prehistoric times Mercury 
and Venus within the orbit of the Earth ; 
Mars, Jupiter and Saturn without. In ad- 
dition there are two distant planets, Uranus, 
almost invisible to the unaided eye, and 
Neptune, completely so ; and many small 
planets, between the orbits of Mars and 
Jupiter, but invisible to the unaided eye 
on account of their great distance. There 
are also numerous comets and their kindred 
bodies, meteors, revolving round the Sun 
and coming within the reach of human vision 
from time to time. 

The Solar System, so far as we know at 
present, is a little under 5,000,000,000 miles 
in diameter, the orbit of Neptune being the 
known boundary. In this system the Earth 
is merely one planet among others ; and it 
is by no means the largest. It comes fifth 
in order of size, being much smaller than 
Jupiter, Saturn, Uranus and Neptune, and 
slightly larger than Venus, Mars and Mercury. 

The Solar System. The Sun, the central 
body of the Solar System, is a huge globe 
about 866,000 miles in diameter. In volume 
it is one and a quarter millions of times greater 



12 PEACTICAL ASTKONOMY. 

than that of the Earth, and its mass is 332,000 
times that of our planet. The Sun is a great 
globe of gaseous matter, at an almost incon- 
ceivably high temperature. The glowing en- 
velope visible to us the photosphere is 
merely the outer surface. This surface is 
diversified from time to time by the appear- 
ance of sun-spots great holes or cavities in 
the photosphere. From these spots it has 
been ascertained that the Sun rotates on its 
axis in about twenty-five days ; at least this 
is the period for the equatorial regions, for 
the vast globe does not rotate as a whole. 
The spots are not always equally numerous. 
They increase and decrease in a period of 
about eleven years. This period is called 
the solar cycle, and is obeyed by the faculse, 
or bright spots on the photosphere, and by 
the prominences or red flames which are 
projected from the chromosphere, a thin 
gaseous envelope surrounding the photo- 
sphere. The corona, the outermost append- 
age of all, varies in shape according to the 
same period. In addition, the variations 
of the magnetic needle and of the aurora 
on earth have a similar period. The dis- 
covery of magnetic fields in sun-spots by the 
American astronomer Hale gives us some idea 
of the nature of the connection. 

The Sun holds sway over a system of bodies 



INTRODUCTORY. 13 

of varying size and condition. We may di- 
vide these into two classes: (1) the planetary, 
and (2) the cometary bodies. The planets fall 
into three subdivisions : (1) the inner planets ; 
(2) the minor planets, or asteroids ; and (3) the 
outer planets. In addition, two of the inner 
and the four outer planets are centres of sub- 
ordinate systems of one or more satellites. 

The inner planets are, in order of distance, 
Mercury, Venus, the Earth, and Mars. Our 
planet is slightly larger than Venus and con- 
siderably larger than Mars or Mercury. Venus 
and Mercury have no satellites ; our Earth 
has one the Moon and Mars has two. 
Comparatively little is known of Mercury 
and Venus. Mercury seems to be a barren, 
rocky world, and it is generally accepted 
among astronomers that its rotation is per- 
formed in eighty-eight days, the same period 
as is required for its revolution round the 
Sun. One hemisphere, accordingly, experi- 
ences everlasting day and the other per- 
petual night. Many astronomers accept a 
similar conclusion in regard to Venus, but the 
evidence is not so strong. The atmosphere 
of Venus is very thick and cloud-laden, and 
very few of its surface-markings are known. 

Mars, on the other hand, rotates on its 
axis in about twenty-four hours thirty-seven 
minutes. The atmosphere of Mars is con- 



14 PRACTICAL ASTRONOMY. 

siderably thinner than that of our Earth, 
and its surface-markings have been mapped 
for two centuries. The disc is diversified 
by reddish-ochre and blue-green areas, while 
at the poles there are white spots which 
wax and wane in accordance with the Mar- 
tian seasons. The reddish-ochre regions, from 
which the planet takes its ruddy tint, are 
known to be deserts, and the blue-green 
areas marshy tracts of vegetation, while 
the polar caps are composed of snow and ice. 
In 1877 Schiaparelli, at Milan, discovered 
the remarkable " canal " system which for 
the last forty years has attracted so much 
attention. The whole surface of Mars is cut 
up by a system of straight dark lines, which 
vary according to the seasons. Many theories 
have been put forward to account for the canal 
system. At present the balance of evidence 
is in favour of the theory of the late Professor 
Lowell of Arizona, based on his study of the 
planet for twenty-two years that the canal 
system is artificial and indicates the existence 
of intelligent life on our neighbouring world. 

Mars appears to represent a later stage in 
planetary development than our Earth. The 
Moon is at a still later period. Long-con- 
tinued study of the Moon has convinced 
astronomers that it is practically a dead world. 
Professor W. A. Pickering's researches have 



INTRODUCTORY. 15 

led him to the conclusion that there is a very- 
thin atmosphere, and that vegetation of a 
low order still exists. But the existence of 
animal life is highly improbable. The lunar 
rotation is performed in exactly the same 
period as its revolution round the Earth. 
One hemisphere is continually turned towards 
us, and the other side has never been seen. 

The asteroids, a group of about 800 tiny 
planets, revolve between the orbits of Mars and 
Jupiter. The largest, Ceres, is about 400 miles 
in diameter ; the smallest are very minute. 
A very tiny asteroid, discovered by Max Wolf 
early in 1918, has a diameter of only four miles. 

The four outer planets Jupiter, Saturn, 
Uranus, and Neptune are very much larger 
than the Earth and its neighbouring worlds. 
The largest, Jupiter, is nearly 90,000 miles in 
diameter. All four seem to be in a condi- 
tion of great internal heat, and it is doubtful 
if solid surfaces exist below their heavy cloud- 
laden atmospheres. Jupiter has nine satel- 
lites four large and five small ; Saturn ten ; 
Uranus four ; and Neptune so far as is 
known one. In addition, Saturn is encircled 
by a wonderful system of rings, composed 
of myriads of tiny meteorites revolving so 
closely together as to be individually indis- 
tinguishable from our world. 

A considerable number of comets are known 



16 PRACITCAL ASTRONOMY. 

to be members of the Solar System, revolving 
round the Sun in very elliptical orbits. These 
comets are not solid bodies like the planets, 
but appear to be collections of loose stones, 
surrounded by gaseous matter. Meteors, or 
shooting-stars, are believed to be the products 
of the dissolution of cometary bodies. 

Let us suppose that the Solar System, 
which is both absolutely and relatively of 
so vast an extent, were co-extensive with the 
visible universe in other words, let us imagine 
for the sake of clearness that the Universe 
were no larger than the Solar System. It 
would be indeed a very large universe, much 
larger than we are able to comprehend. The 
Sun would rise and set as at present ; it 
would ascend to its highest point in summer 
and descend to its lowest point in winter. 
The Moon would pass through its cycle of 
changes in its revolution round the Earth. 
The planets would make their periodical ap- 
pearances, shining brilliantly on an inky black 
sky. Usually there would be some object 
visible in this black sky ; on moonless nights 
one or two planets would probably be seen, 
but there would be evenings on which the 
heavens would be absolutely black. For 
there would be no stars. 

Thus by imagining the heavens without 
stars, we are enabled at once to assign to the 

(2,015) 



INTRODUCTORY. 17 

stars their true position in the order of nature. 
The stars are luminaries far outside of the 
Solar System ; the stars, in fact, are not worlds 
in any way analogous to the planets ; they are 
themselves suns similar to the central body 
of the Solar System. It is true that when 
we see a planet on the background of stars 
it appears much more brilliant. Jupiter, for 
instance, shines many times more brightly 
than Sirius, the brightest of the stars ; and 
yet Jupiter in comparison with even the 
faintest star which we see twinkling in the 
field of the telescope is utterly insignificant. 
It belongs altogether to an inferior order of 
bodies ; it is merely the attendant of a star. 
Thus we see that one effect of the great dis- 
tance of the stars is to make them seem very 
insignificant bodies. 

Another effect of their distance is that their 
motions are to the ordinary observer abso- 
lutely imperceptible. One of the great truths 
of modern astronomy is that the so-called 
" fixed " stars are in motion in various direc- 
tions and with different velocities ; but so 
great is their distance that these motions can 
only be noted after the lapse of many years, 
with the aid of powerful instruments and 
exact measurements. Were Homer or Hesiod 
or the author of the Book of Job alive to-day, 
they would see the same constellations and 

(2,015) 2 



18 PRACTICAL ASTRONOMY. 

stars with which they were familiar. They 
would behold apparently unchanged the 
*' bands " of Orion and the Pleiades and 
" the Bear with her train." 

Thus to us the stars are the background of 
the Solar System the setting to the drama 
of the planetary motions. And as such the 
stars were treated for many years. They were 
observed mainly as convenient reference- 
points for the observation of the positions 
of the Moon and planets. Since the days of 
Sir William Herschel, however, the stars have 
been observed and studied for their own sake. 

The stars then are the distant background 
of the Solar System. Thus when we read in 
astronomical almanacs or in the newspaper 
press that " Mars is in Aries " or " Jupiter is 
in Taurus," it is necessary for us to remember 
that seen from the Earth, Mars is in the same 
line of vision as the stars in the constellation 
Aries ; that the constellation Taurus is the 
background against which Jupiter is seen. 

We must also bear in mind that the stars 
are not a real background, but only an ap- 
parent one. The constellation Taurus, for 
instance, is not a collection of bodies all at 
the same distance from the Solar System. 
Some of the stars in the constellation form 
connected groups and systems, but the con- 
stellation is not necessarily a unity. In 



INTRODUCTORY. 19 

other words, the stars are at different dis- 
tances. Sirius, for instance, the brightest 
star in the sky, is much closer to the Earth 
than Kigel in the neighbouring constellation. 

The stars are at various distances. To 
make this clear, a simple illustration may be 
given. Two stars, let us say of equal bright- 
ness, appear close together in the heavens. 
They may form a connected system, but not 
necessarily. One may be much closer to the 
Solar System than the other, and they may 
appear close together merely because they 
happen to lie in the same line of vision. It is 
quite a mistake to suppose that the brightest 
stars are necessarily the nearest. Sometimes 
they are so, sometimes they are not. For 
instance, an insignificant star of the fifth 
magnitude in the constellation Cygnus is 
nearer to the Earth than Sirius, the brightest 
star in the sky. 

Distance of the Stars. Something remains 
to be said of the distance and magni- 
tude of the stars. We have seen that the 
diameter of the Solar System is a little under 
5,000,000,000 (five thousand million) miles. 
The principle of the measurement of star- 
distance has been explained by Mr. Maunder 
in another volume of this series, and it is only 
necessary to give one or two examples of the 
distances of the stars. The nearest star is 



20 PRACTICAL ASTRONOMY. 

only visible in the southern hemisphere. It 
is the brightest star of the constellation Cen- 
taurus and is known as Alpha Centauri, and 
the distance of this orb is about twenty-five 
billions of miles. It is almost impossible to 
realise this vast distance, but an idea may be 
gained from consideration of the fact that if 
the distance from the Sun to Neptune, the 
most distant planet of the Solar System, were 
represented by 10 feet, the nearest star would 
be fourteen miles away. The great distance 
of the stars may be better realised in another 
way. The rays of light, which travel from 
the Moon to the Earth in a second and a half, 
with a velocity of 186,000 miles per second, 
cross the diameter of the Solar System in 
eight hours. Four years are required for 
light to travel from the nearest star. 

Magnitudes of the Stars. The stars, as we 
have seen, are situated at all distances from 
the Solar System, and probably they are 
of all sizes. Yet their apparent brilliance 
does not on the whole depend on distance or 
size alone, but on both. One bright star 
may be comparatively near and of moderate 
size, another may be very distant and of im- 
mense dimensions. The stars are divided 
into magnitudes according to their apparent 
brightness ; and six magnitudes of stars are 
within reach of the unaided eye. There are 



INTRODUCTORY. 21 

about twenty stars of the first magnitude and 
sixty of the second. Some of the constella- 
tions, as will be explained, are very rich in 
bright stars, others very poor. 

The brightest stars have proper names. 
Thus the brightest star of Canis Major is 
known as Sirius, and the brightest star of 
Taurus is known as Aldebaran. These proper 
names were given to the stars by the early 
astronomers, Greek and Arabian. When the 
stars came to be catalogued and charted it 
was necessary to designate them individually. 
Accordingly the brighter stars in each constel- 
lation are known by the letters of the Greek 
alphabet. Thus Aldebaran is also Alpha 
Tauri (literally Alpha of Taurus, " Tauri " 
being the Latin genitive), Sirius is Alpha 
Canis Ma j oris. When the Greek letters be- 
come exhausted, numbers are used. 

The Stellar Universe. Just as the Earth 
and the other planets form a system of worlds 
revolving round the Sun, so the Sun and the 
other stars also form a connected system on 
a much vaster scale. While the planets are 
separated by millions of miles, the distances 
between the individual stars are to be 
reckoned by billions. 

Much information has been collected con- 
cerning individual stars their distances and 
masses and concerning double and variable 



22 PRACTICAL ASTRONOMY. 

stars. But two important generalisations 
stand out clearly. The stars are aggregated 
towards the Milky Way or Galaxy. If we 
compare the Stellar System to a great globe, 
the Galaxy may be likened to its equator. 
There is a progressive increase in the number 
of stars as the Galaxy is approached, and the 
galactic region seems to be both a region of 
greater condensation and of greater extension in 
the line of sight. Some of the distant star-clouds 
of the Galaxy are so far away that light requires 
thousands of years to travel to the Earth. 

Another important generalisation has been 
established in recent years by the researches 
of Kapteyn, Eddington, Dyson and others. 
The motions of the great mass of the stars 
^s far as is at present known are not at 
random ; there is a drift of the stars in two 
well-defined directions. Various hypotheses 
have been put forward to account for this, but 
no satisfactory conclusion has yet been reached. 
One point is clear there is no " central sun " 
among the stars : the Stellar System is not 
analogous to the Solar System. Elammarion, 
in one of his happy illustrations, compares the 
Solar System to an absolute monarchy with the 
Sun as despot, and the system of the stars to a 
federal republic with no dominating authority. 

It has been computed that there are in the 
Stellar System about 500,000,000 stars, and 



INTRODUCTORY. 23 

several thousands of gaseous nebulae ; but, 
nevertheless, it appears to be strictly limited 
in extent. Like the Solar System, this greater 
Stellar System seems to be merely one among 
others. Recent research makes it probable that 
some of the isolated star-clusters and many of 
the spiral nebulae are external, though prob- 
ably smaller and perhaps dependent, systems 
plunged at vast distances in space. It has 
been computed that the cluster in Hercules, 
one of the nearest, is situated at a distance so 
great that light requires 100,000 years to travel. 
We are confronted then with an ascending 
scale of world-systems. First of all, we have 
the little terrestrial system the Earth and 
Moon and other satellite systems within the 
greater Solar System ; secondly, the Solar 
System is merely one of millions of other 
systems, components of the greater Stellar 
System ; thirdly, the Stellar System vast, 
almost infinitely vast in extent though it be 
appears to be but one of a number of similar 
systems scattered throughout the infinite ex- 
tent of space. The human mind is unable to 
conceive this apparently endless profusion of 
suns and systems and systems of systems. We 
pause awe-stricken before what Shelley a century 
ago called 

" This interminable wilderness 
Of worlds, at whose immensity 
Even soaring fancy staggers." 



24 PRACTICAL ASTRONOMY. 

We are face to face with infinity the eternal, 
the illimitable, the unthinkable. In the words 
of the poet Richter, " The spirit of man acheth 
with this infinity " ; for " end is there none 
to the Universe of God. Lo ! also there is 
no beginning." 



CHAPTER II. 

THE NORTHERN STARS. 

The positions of the stars in the sky are sub- 
ject to two periodical changes the hourly 
change and the seasonal change. The former 
is due to the rotation of the Earth on its axis 
and the latter is due to its revolution round 
the Sun. Even the casual observer can see 
that the stars rise and set like the Sun and 
that different stars are visible at different 
seasons. 

Owing to the rotation of the Earth on its 
axis the entire star-sphere appears to move 
round our world once in twenty-four hours ; 
and owing to the revolution of the Earth 
round the Sun, the orb of day appears to move 
among the stars, or rather, the stars appear 
to drift westward into the sunset, rising and 
setting four minutes earlier each night. 

The Earth rotates on an axis which is 



THE NORTHERN STARS. 25 

inclined to the plane or level of the terrestrial 
orbit round the Sun by about sixty-seven 
degrees, and to the perpendicular by about 
twenty- three degrees. The result is that some 
stars rise and set like the Sun, others are never 
to be seen, while others again neither rise nor 
set, but seem to circle round a fixed point in 
the sky, and are continually visible whenever 
the sky is clear and the Sun absent. In a 
survey of the heavens, it is wise to commence 
with the stars which are continually visible 
the circumpolar stars of the northern hemi- 
sphere. 

The Plough. The axis of the Earth points 
to a part of the heavens very close to a bright 
star of the second magnitude known as the 
Pole Star, which remains practically stationary 
in the heavens. But the Pole Star is not the 
most suitable object from which to commence 
a study of the circumpolar stars. There is 
no question that the large constellation of 
Ursa Major, or the Great Bear or a part of 
it is the conspicuous object of the northern 
heavens. No one can mistake the seven stars 
known variously as the Plough, Charles's 
Wain and in America the Dipper. These 
stars have been noted and observed from the 
earliest ages ; they are referred to by Homer 
and Hesiod and in the Book of Job. 

The Plough is seen to best advantage in 



26 PRACTICAL ASTRONOMY. 

autumn, when it is due north and compara- 
tively low down in the heavens ; there can 
then be no difficulty in identifying the group. 
The northern heavens are not especially rich 
in bright stars, and in the autumn evenings 
the Plough is visible either slightly tilted to 
the north-west, due north, or slightly tilted 
to the north-east, according to the hour of 
the night or the time of the season. For 
instance, at ten o'clock in the beginning of 






Fig. 1. The Plough. 

October the Plough is directly north, a month 
later at the same hour it is slightly tilted to 
the north-east ; but it is unnecessary here to 
mention the various days and hours on which 
the Plough is to be seen in different positions. 
Once the configuration of the constellation is 
implanted in the mind, there will be no diffi- 
culty in picking it out, whatever its position. 

In the winter evenings, generally speaking, 
the Plough is in the north-east ascending in 



THE NORTHERN STARS. 27 

the heavens. As the hours pass on during 
the same evening, or as the season progresses 
at the same hour, the Plough rises higher 
and higher in the heavens until in spring it 
is practically in the zenith in the hours fitted 
for observation. This is the season when it 
is most difficult to recognise the Plough. If, 
however, we are familiar with it before, it 
is quite easy to identify the well-known figure 
high in the sky. In summer, the Plough is 
to be seen in the north-west, descending as 
the season advances. 

On the whole it may safely be said that the 
autumn is the best season for a beginner, who 
knows nothing of the constellations and has 
never seen the Plough, to commence his 
studies. Obvious at all times, the Plough is 
absolutely unmistakable in the autumn even- 
ings. There are seven stars in the constella- 
tion, six of which are, roughly speaking, of 
the second magnitude and one of the fourth. 
Proceeding from the front of the Ploughshare 
backwards to the handle, the stars are desig- 
nated by the first seven letters of the Greek 
alphabet Alpha, Beta, Gamma, Delta, Ep- 
silon, Zeta, and Eta. They are also known 
by Arabic names. Alpha is " Dubhe," Beta 
is "Merak," Gamma is " Phecda," Delta is 
"Megrez," Epsilon is " Alioth," Zeta is 
"Mizar," and Eta is " Alkaid " or " Benet- 



28 PEACTICAL ASTRONOMY. 

nasch." Of these names, only the sixth, 
Mizar, is commonly used. 

Two of the stars in the Plough call for special 
mention, Delta and Zeta. Delta is generally 
believed to have been at one time of the second 
magnitude, whereas it is now of the fourth, 
so it would seem to have decreased in brilliance. 
Zeta, generally known as Mizar, is a remark- 
able star. A keen eye can detect the fact 
that it is double, or rather that there is a faint 
companion star near. This little star is known 
as Alcor, and in the binocular the two make a 
striking spectacle. With a moderate tele- 
scope Mizar is seen to be itself double. 

The Plough is only part of the constellation 
Ursa Major, but it is much the more conspicu- 
ous part. The remaining stars of the con- 
stellation are much fainter and much more 
difficult to trace. 

The Pole Star. Alpha and Beta of Ursa 
Major are known as " The Pointers," because 
a straight line joining these two stars points 
directly to the Pole Star. Once these two 
stars are known, it is impossible to mistake 
the Pole Star. It is noticeable as being the 
next conspicuous star in the line with the 
Pointers. As its name indicates, the Pole 
Star approximately marks the point in the 
heavens to which the Earth's axis points. 
To an observer at the North Pole, the Pole 



THE NORTHERN STARS. 29 

Star would appear almost exactly overhead ; 
to an observer at the equator, it would seem 
almost exactly on the horizon. In our lati- 
tudes, the altitude of the Pole Star above the 
horizon varies with the latitude of the place 
from which it is observed. To the ordinary 
observer, the star seems stationary in the 
heavens, the one point around which the 
other stars describe circles. In reality its 
position does not exactly coincide with the 
celestial Pole ; it actually describes a very 
small circle, and there are several stars nearer 
to the Pole, which are practically invisible 
without the aid of a binocular the chief of 
these being Lambda of Ursa Minor, which is 
just visible to the unaided eye. 

The Pole Star is the chief star of Ursa Minor 
or the Little Bear, and is also known as Alpha 
Ursae Minoris. The constellation Ursa Minor, 
like the more conspicuous Ursa Major, has 
seven principal stars. Proceeding in a curve 
from the Pole Star these are Delta, Epsilon, 
Zeta, and Beta ; while Gamma and Eta form 
a square with Beta and Zeta. Beta and 
Gamma are the only noticeable stars of the 
constellation except the Pole Star. 

Cassiopeia. Once the Plough and the 
Pole Star have been identified, the task of 
learning the arrangement of the northern 
stars is much simplified. If we keep the 



30 PEACTICAL ASTEONOMY. 

Plough and the Pole Star in view it is easy 
to identify another notable constellation. On 
the exactly opposite side of the Pole Star 
from the Plough and at about the same dis- 
tance is a star-group almost as conspicuous, 
though smaller than the Plough itself. This 
is Cassiopeia or the Lady in the Chair. The 
shape is easily remembered ; it is like the 
letter W. In the evenings of spring-time, 
when the Plough is almost overhead, Cas- 
siopeia is visible low down 
in the north. It is then to 
# be seen to the best advan- 

K tage and its W-shape is 

h t #0 mos ^ obvious. In summer, 
^m when the Plough is de- 

# x scending to the north-west, 
rt _ f . we see Cassiopeia ascend- 

Fig. 2. Cassiopeia. . , . \. A T 

mg in the north-east. In 
autumn, when the Plough is low down in 
the north, Cassiopeia is almost exactly over- 
head ; and in winter, when the Plough is 
ascending in the north-east, Cassiopeia is 
descending in the north-west. Small though 
it is in extent, Cassiopeia is one of the 
most prominent constellations in the sky 
on account of the brightness of its stars and 
its symmetrical shape. Beginning at the 
right-hand corner of the W-shaped figure, 
the five chief stars are Beta, Alpha, Gamma, 



THE NORTHEKN STARS. 31 

Delta, and Epsilon. Beta, Alpha, and Gamma 
are of the second magnitude, and Delta and 
Epsilon are of the third. Kappa, though 
faint of the fourth magnitude is prominent 
by reason of its position. It forms a trapezium 
with Beta, Alpha, and Gamma. Another faint 
star which is easily identified by reason of its 
position is Iota, which is in a straight line with 
Delta and Epsilon. 

The constellation is one of the richest in the 
heavens, and in this it differs from its com- 
panion star-group, the Plough. Ursa Major 
is situated in a barren portion of the sky. 
Cassiopeia is fully immersed in the stream of 
the Milky Way or Galaxy. The Milky Way 
is one of the best-known celestial phenomena. 
As Mr. Maunder has explained in a previous 
volume of this series, the Milky Way is the 
" foundation of the celestial building." It 
is the ground-plan of the Universe. It is 
nothing more nor less than the region of the 
heavens in which the stars are most closely 
crowded together. To the unaided eye it 
presents the appearance of a belt of milky 
light across the sky ; and in this belt, not at 
the broadest, but at one of its brightest parts, 
the chief stars of Cassiopeia are immersed. 
To the observer with a binocular, Cassiopeia 
is a particularly interesting field for observa- 
tion. The star Gamma is the centre of one 



32 PRACTICAL ASTRONOMY. 

of the most remarkable regions in the heavens 
in regard to the symmetrical arrangement of 
the stars ; it is also very crowded. 

The constellation is also famous in the 
history of astronomy owing to the fact that 
the most brilliant temporary star which has 
been recorded shone out near Kappa in August 
1572. This star was particularly studied by 
the famous astronomer Tycho Brahe, who, 
although he did not discover it, observed it 
so patiently and systematically and left so 
complete an account of its variations that it 
has always been known as " Tycho's Star." 
One evening in November 1572 the astronomer, 
on casting his glance upwards, was astounded 
to notice the familiar appearance of Cassiopeia 
completely changed by the presence of a new 
and brilliant star which far outshone the other 
stars in the constellation. When first seen by 
Tycho it was as bright as Jupiter, and when 
it reached its maximum it was equal to Venus 
in brilliancy, being visible in full daylight. 
Steadily declining, it ceased to be visible to 
the unaided eye a year and a half after its 
appearance. 

Capella and Vega. Having identified the 
Plough, the Pole Star and Cassiopeia, it is 
comparatively easy for the observer to find 
the other important northern stars. As al- 
ready mentioned, the Plough and Cassiopeia 



THE NORTHERN STARS. 33 

are on opposite sides of the Pole Star. There 
are two stars, also on opposite sides of the 
Pole, which are useful guiding stars not only 
for the northern heavens but also for the stars 
which rise and set. On account of their 
brilliance, Capella (Alpha Aurigae) and Vega 
(Alpha Lyrae) cannot be mistaken ; and al- 
though these are at least in Scotland cir- 
cumpolar stars visible all the year round, 
Auriga and Lyra cannot properly be described 
as circumpolar constellations. Capella is the 
prominent star of the first magnitude between 
Cassiopeia and the Plough. In the autumn, 
when the Plough is due north and Cassiopeia 
nearly in the zenith, Capella is ascending in 
the north-east. In winter, when the Plough 
is ascending in the north-east and Cassiopeia 
descending in the north-west, Capella is to 
be seen almost overhead, while Vega is prac- 
tically lost in the haze of the horizon. In 
spring, when the Plough is nearly overhead 
and Cassiopeia low down in the north, Capella 
is descending in the north-west and Vega 
ascending in the north-east. In summer, 
when the Plough is descending in the north- 
west and Cassiopeia ascending in the north- 
east, Vega is nearly overhead, while Capella 
is practically lost in the haze of the horizon. 

Vega and Capella will be more fully de- 
scribed in the chapters on the summer and 

(2,015) 3 



34 PRACTICAL ASTRONOMY. 

winter constellations respectively ; but it is 
essential that these two stars should be known 
soon after the Plough and Cassiopeia. 

Cepheus. There are other two northern con- 
stellations, less conspicuous than those men- 
tioned, which it is well to identify. These are 
Cepheus and Draco. The former constellation 
adjoins Cassiopeia. When Cassiopeia is low 
down in the north Cepheus is above Cassiopeia 
to the right, and practically immersed in the 
stream of the Milky Way. 

The stars Alpha, Beta, Iota and Zeta form 
a well-marked trapezium. All four are of the 
third magnitude. Within the trapezium and 
nearly in the centre is Xi Cephei, of the fifth 
magnitude. Gamma Cephei forms a triangle 
with Iota and Beta ; it is of the third mag- 
nitude and comparatively close to the Pole 
Star, with which it is in line. Another much 
smaller triangle is formed by Zeta, Epsilon 
and Delta. Delta is a variable star the 
brightest of the important and numerous 
class known as " Cepheids." It varies from 
the third magnitude to the fourth in 5 days 
8 hours 7 minutes 40 seconds. Mu Cephei, of 
the fourth magnitude, lies between Alpha and 
Zeta, below an imaginary line joining them. 
It is probably the reddest star visible to the 
unaided eye in the northern hemisphere, and 
was named by Sir William Herschel " the 



THE NORTHERN STARS. 35 

garnet star." Seen in the binocular, Mu 
Cephei is a very striking and beautiful object. 

Draco is one of the most difficult constella- 
tions to follow. It adjoins Cepheus and winds 
along the barren reaches of the sky near Ursa 
Minor, and ends in a line of stars parallel to 
the Plough Alpha, of the third magnitude, 
is on a line with Zeta Ursae Ma j oris (Mizar), 
Lambda is on line with Alpha Ursae Majoris ; 
while Kappa is the star between Alpha and 
Lambda. The constellation coils round the 
sky until it joins Cepheus ; then it curves 
round again and terminates in three bright 
stars Xi, Beta and Gamma near the bound- 
aries of the constellation Hercules. These 
three stars with Iota Herculis form a diamond- 
shaped figure. 

There are other constellations partly cir- 
cumpolar Cygnus, Perseus and Andromeda, 
but these are practically invisible at certain 
periods and will be discussed among the stars 
of the respective seasons. 

We have now completed a survey of the 
northern stars which are visible all the night 
and all the year round. Beginning with the 
Plough, the observer will recognise the Pole 
Star and Cassiopeia, and by means of these 
he will identify Capella and Vega, the two 
watchers of the northern heavens. There is 
something awe-inspiring in contemplating the 



36 PRACTICAL ASTRONOMY. 

ceaseless revolution of these stars, and this 
feeling is not diminished by the recollection 
that the motion we are watching is that of 
our own world projected on the sphere. As 
an able writer has expressed it : " To watch 
these northern constellations as they follow 
each other in regular ceaseless procession 
round the Pole is one of the most impressive 
spectacles to a mind capable of realising the 
actual significance of what is seen. We are 
spectators of the movement of one of Nature's 
machines, the vastness of the scale of which 
and the absolutely perfect smoothness and 
regularity of whose working so utterly dwarf 
the mightiest work accomplished by man." 



CHAPTER III. 

THE STARS OF WINTER. 

In the previous chapter a description was 
given of what are known as the circumpolar 
stars those stars in the northern heavens 
which are situated so close to the Pole that 
they do not rise nor set, but circle ceaselessly 
round. They are to be seen every clear night, 
in positions varying with the changing seasons. 
The majority of the stars, however, are not 
thus situated. They have their seasons of 



THE STARS OF WINTER. 37 

visibility and invisibility, of favourable and 
unfavourable positions, depending on two 
factors their apparent distance from the 
Pole and their position with respect to the 
Sun. As mentioned in the previous chapter, 
as the distance of a star from the Pole in- 
creases, the circle which it describes grows 
wider and wider. Some constellations, such 
as Perseus, Andromeda and Auriga, are partly 
circumpolar partly seasonal. The circles 
which they describe only pass very slightly 
below the northern horizon. Other constella- 
tions, such as Gemim and Bootes, pass below 
the horizon for a slightly longer period ; but 
such groups always rise in the north-east and 
set in the north-west. Other groups farther 
from the Pole, such as Orion, rise almost due 
east and set almost due west ; while others 
again merely ascend a little distance above 
the southern horizon, rising in the south-east 
and setting in the south-west. 

Owing to the apparent motion of the Sun 
among the stars, or, as it appears to us, the 
apparent drifting of the stars into the sunset 
twilight, these stars which rise and set have 
their particular seasons of visibility. The 
nearer the constellation is to the Pole the 
longer its period of visibility. For instance, 
Auriga only disappears from view for a short 
time. The farther a constellation is from the 



38 PKACTICAL ASTKONOMY. 

Pole, the shorter the period during which it 
is visible. This is the case with Canis Major, 
Lepus, Scorpio and other groups which never 
rise far above the southern horizon. 

Even those stars which are visible almost 
all the year round are seen to most advantage 
in certain seasons ; and the easiest way to 
learn the various star groups is to discuss them 
season by season. 

We begin with the stars of winter, for two 
chief reasons. In the first place, the winter- 
time is the season when astronomical ob- 
servation is easiest. The long dark evenings 
are the most favourable for the study of the 
heavens. In the second place, the winter 
constellations are the most brilliant and most 
easily identified. It is a curious fact that the 
stars visible in the winter months are far more 
beautiful and striking than those to be seen 
in spring, summer or autumn. As Flammarion 
has truly remarked : " Nature everywhere 
establishes harmonious compensation, and 
whilst it darkens our short and frosty days it 
gives us long nights enriched with the wealth- 
iest creations of the heavens." 

Orion. In some guides to the stars direc- 
tions are given to identify the brilliant winter 
stars by means of lines drawn from the Plough 
or Cassiopeia. In reality no such method is 
necessary ; for Orion, the leader of the winter 



THE STARS OF WINTER. 39 

constellations, is the most brilliant of all the 
star-groups, and is always visible at a con- 
venient altitude for observation. It rises al- 
most due east, culminates midway between 
the horizon and the zenith, and sets almost 
due west. Once seen, Orion can never be 
forgotten. In the early evening in November 
and December, it is visible rising in the south- 
east ; later in the season it reaches the me- 
ridian, or point due south. In 
February and March it is de- ^ 
scending in the south-west. 

A large proportion of people, 
who have no particular interest ^~ 

in astronomy, are familiar with #^ 
Orion. The figure is easily re- 
membered. An irregular quad- , 
rilateral is formed by the four 3 
bright stars, Alpha, Gamma, K 
Beta and Kappa. In the centre FlG ' 3 -- BION - 
of this quadrilateral are three stars almost 
equally bright, nearly in a straight line slant- 
ing downwards. These are Delta, Epsilon 
and Zeta. 

Of these seven stars two, Alpha and Beta, 
are of the first magnitude, and five, Gamma, 
Kappa, Delta, Epsilon and Zeta, of the second. 
Alpha, at the north-east or top left-hand corner 
of the quadrilateral, is more familiarly known 
by its Arabic name Betelgeux. It is a very 



40 PRACTICAL ASTRONOMY. 

conspicuous object, shining with a red light 
which contrasts with the bluish- white radiance 
of Rigel. Generally, Betelgeux is inferior in 
brilliance to Beta Orionis, more commonly 
known as Rigel, the star in the south-west, 
or the bottom right-hand, corner of the quad- 
rilateral ; but at times it increases in bright- 
ness and outshines Rigel. Its variations are 
irregular, but easily followed. It is generally 
believed to have been brighter than Rigel in 
1603, when the Greek letters were assigned to 
the individual stars. At that date it was 
designated Alpha, indicating that it was 
then the chief star of the constellation. 

These two stars, Betelgeux and Rigel, have 
been much studied by astronomers. Both are 
so far distant from the Earth that it cannot 
be said that the attempts to measure their 
distance have met with success. Approximate 
measurements, however, have been made. 
Betelgeux is at least over 20,000 times more 
massive than the Sun. It is, as already men- 
tioned, a red star, as its atmosphere is much 
heavier than that of our orb of day. As the 
subject of spectroscopic astronomy is dealt 
with in another volume of this series, it is 
unnecessary to mention the methods by which 
astronomers have reached their conclusions 
concerning these stars. Betelgeux is, as al- 
ready mentioned, a variable star ; and vari- 



THE STABS OF WINTER. 41 

able stars of this particular type are generally- 
red in colour. 

Rigel, on the other hand, is bluish-white in 
colour, shining with a clear light. Its only 
points of resemblance to Betelgeux are its 
immense distance and enormous size. Its 
distance cannot be measured, but astronomers 
have calculated the minimum distance at 
which it can be placed. It is placed, even on 
the minimum estimate, at a distance so vast 
that light, which travels from the Sun in 8 
minutes and from the boundaries of the Solar 
System in 4 hours, requires no less than 307 
years to cross the mighty void. It must be a sun 
of enormous size, probably one of the greatest 
bodies in the entire Universe ; its mass is at least 
37,000 times that of the Sun, and, as we know, 
the Sun is inconceivably larger than the Earth. 

Gamma Orionis, in the north-west or top 
right-hand corner of the quadrilateral, is fre- 
quently known by its Arabic name Bellatrix. 
At the south-east corner of the figure is Kappa, 
also of the second magnitude. 

The most famous object in the constellation 
is, however, the Great Nebula in Orion. It 
surrounds Theta Orionis, the middle star of 
the " Sword of Orion," which consists of three 
faint stars in a straight line with Epsilon, the 
middle star of the belt. On a clear night a 
keen eye can detect a haziness about Theta 



42 PKACTICAL ASTRONOMY. 

which a binocular shows to be a cloud of 
misty light. Even in a small telescope it is 
a striking spectacle. The haziness expands 
into a magnificent cloud-like object, and its 
apparent size increases as the telescope em- 
ployed becomes larger. The nebula is a 
gigantic mass of glowing gas, thousands of 
times larger than the Solar System. Photog- 
raphy has shown the nebula to be vastly 
more, extended than it appears to be when 
studied with the telescope ; indeed the whole 
constellation has been ascertained to be 
wrapped in nebulous haze. 

Orion, as the most conspicuous of the con- 
stellations, has been known from the earliest 
ages and is referred to by the early writers. 
Homer refers to Orion, while we are all familiar 
with the well-known passage in the Book of 
Job, " Canst thou loose the bands of Orion ? " 

Canis Major and Canis Minor. Orion is 
the index-constellation of the winter star- 
groups in the southern aspect of the heavens. 
Betelgeux forms a very conspicuous equilateral 
triangle with two other bright stars, Sirius in 
Canis Major and Procyon in Canis Minor. 
As the old rhyme has it : 

" Let Procyon join to Betelgeux and pass a line afar, 
To reach the point where Sirius glows, the most conspicuous 

star, 
Then will the eye delighted view a figure fine and vast, 
Its span is equilateral, triangular its cast." 



THE STAES OF WINTER. 43 

The great triangle is one of the most notice- 
able configurations in the entire heavens ; 
its striking appearance being due to the bril- 
liance of the three stars composing it and to 
the dearth of stars within. Procyon, a star 
of the first magnitude, is the chief star Alpha 
of Canis Minor or the Little Dog. It is the 
only conspicuous star in an inconspicuous 
constellation. More striking in its appearance 
is Canis Major or the Great Dog. This group 
is famous as containing Sirius Alpha Canis 
Majoris the brightest star in the sky. Sirius 
is never to be seen very high in the heavens 
in these latitudes, rising in the south-east and 
setting in the south-west. The " Dog Star " 
has been termed " the monarch of the skies," 
and so far as mere brilliance is concerned fully 
merits the title. Much of its brilliance, how- 
ever, is due to the fact that it is comparatively 
one of our nearer neighbours in space. Light 
requires eight years to reach us from the Dog 
Star, as compared with hundreds of years from 
Betelgeux and Rigel. Therefore, although 
Sirius is probably considerably larger than our 
Sun, it is relatively a small star in comparison 
with other orbs which appear its inferiors on 
account of their greater distance. Sirius is a 
well-known double star, but the satellite can 
only be seen in powerful telescopes. 

Taurus. Higher in the sky than Orion are 



44 PKACTICAL ASTRONOMY. 

two brilliant constellations, Taurus and Gremini. 
It is impossible to mistake the two groups. 
Taurus is north-west of Orion, Gremini north- 
east. Taurus is the second of the twelve con- 
stellations of the Zodiac, through which the 
Sun moves on its apparent path round the 
Earth, while Gremini is the third. Of the 
two Taurus is the more famous, as it contains 
the two well-known star-clusters, the Hyades 



v 



* 



Fig 4. Taurus. 



# > 



and the Pleiades. The former is a group of 
five stars arranged like the letter V. The 
brightest star of the Hyades, and indeed of 
the constellation, is Aldebaran or Alpha 
Tauri, which marks the upper left hand of 
the figure. Epsilon, of the fourth magnitude, 
marks the upper right hand, and Gamma, also 
of the fourth magnitude, the angle. Aldebaran 
is by far the most conspicuous star ; it is of a 
bright red colour and indeed closely resembles 



THE STAES OF WINTER. 45 

Betelgeux in the neighbouring constellation. 
The distance of Aldebaran has been measured 
with some approach to certainty, and its mass 
is believed to be about two hundred times 
that of the Sun. 

The Pleiades. Higher in the sky than Alde- 
baran and the Hyades, and on the right- 
hand side of these stars, is the most famous 
star-cluster in the entire heavens the Pleiades. 
Like the Plough and Orion, this cluster has 
attracted the attention of man from prehistoric 
times. " Canst thou bind the cluster of the 
Pleiades ? " asks the Creator of Job in that 
Book of the Bible.* Hesiod too says of the 
Pleiades, 

" There is a time when forty days they lie 
And forty nights, concealed from human eye," 

referring to their invisibility when the Sun is 
passing through Taurus. 

The Pleiades begin to appear in the late 
evenings of autumn, above the eastern horizon. 
At this season we, like Tennyson's hero of 
Lochsley Hall, behold 

"... the Pleiades rising through the mellow shade 
Glittering like a swarm of fire-flies tangled in a silver braid." 

The name " Pleiades " is probably derived 
from the Greek " Pleiones," many or full. 
The stars are closely packed together. Six 

* Revised Version. 



46 PRACTICAL ASTRONOMY. 

stars, the brightest of which is Alcyone, or 
Eta Tauri, are visible to a person of average 
sight, but a very keen eye will discern as many 
as twelve or fourteen. The binocular changes 
the entire aspect of the cluster, revealing many 
more stars, while in the telescope many hun- 
dreds may be seen. Since the invention of 
the telescope the cluster has received its full 
share of attention. The photographic plate 
has shown it to consist of thousands of stars ; 
and not the least interesting of the revelations 
of photography has been the discovery that 
the group of the Pleiades is not a cluster pure 
and simple, but that the stars composing it 
are embedded in nebulae, masses of incan- 
descent gas. The cluster seems to be in a 
chaotic condition, and the stars composing it 
are generally considered to be at an earlier 
stage of evolution than our own Sun. 

Gemini Next to Taurus, and to the left 
of Orion, is the constellation Gemini or the 
Twins. Gemini is chiefly notable for the two 
bright stars, Castor and Pollux, on the eastern 
boundary of the constellation. Castor is des- 
ignated as Alpha Geminorum and Pollux as 
Beta Geminorum. Here we have a case 
similar to that of Alpha and Beta Orionis ; 
Pollux is brighter than Castor. It is generally 
believed that Castor has decreased in brilliance 
since the stars received their Greek letters. 



THE STARS OF WINTER. 47 

Castor is a double star, but is not within the 
reach of the binocular. On the right-hand 
side of the constellation is a square formed by 
four stars Epsilon, Mu, Gamma and Zeta. 
Epsilon and Mu are of the third magnitude 
and Gamma of the second ; while Zeta is a 
well-known variable, fluctuating from the 
third to the fourth magnitude in 10 days 3 
hours. It can be easily followed with the un- 
aided eye or binocular. Zeta forms an equi- 
lateral triangle with other two stars, Delta of 
the third magnitude and Lambda of the fourth. 
Finally, close to Mu is a noticeable star Eta, of 
the third magnitude although slightly variable. 

Lepus and Eridanus. Returning to Orion, 
it is well to note the inconspicuous constella- 
tions close to it, Lepus and Eridanus. Lepus 
the Hare is exactly underneath the magnifi- 
cent star group. There is nothing remarkable 
about this constellation ; its four chief stars, 
Alpha and Beta of the third magnitude and 
Gamma and Delta of the fourth, form the 
corners of an irregular quadrilateral. Eridanus 
is a much less compact constellation. It 
straggles from close to Orion to the boundaries 
of Cetus, and then curves downwards into the 
southern hemisphere. Beta Eridani, of the 
third magnitude, can be easily identified from 
its proximity to Rigel. 

Auriga. A survey of the winter constella- 



48 PKACTICAL ASTRONOMY. 

tions is incomplete without reference to one 
of the most remarkable of all, namely Auriga. 
Starting from Orion, the guiding constellation 
of winter, it is easy to recognise Auriga. Above' 
Orion, as we have seen, are Taurus and Gemini, 
the bright stars of which are on either side of 
the space immediately above Orion. Above 
these two, and therefore directly above Orion 
and almost in the zenith, is Auriga. This 
group, which, as mentioned in the preceding 
chapter, is almost a circumpolar constellation, 
is of the shape of an irregular pentagon, with 
one of its sides much shorter than the rest. 
The stars forming the corners of the figure are 
Alpha or Capella, Beta, Theta, Iota and Ep- 
silon. Capella is of the first magnitude and 
one of the most brilliant of all the stars. It 
is a star of the same type as our Sun, only 
very much larger and more massive ; in 
recent years, it has been found by means of 
the spectroscope to be an exceedingly close 
double star. Beta, of the second magnitude, 
has also been found to be double by the 
same method. Theta, Iota and Epsilon are 
of the third magnitude, but do not call for 
special mention. Epsilon forms an isosceles 
triangle with Eta and Zeta, two stars of the 
fourth magnitude very close together. In 
Auriga appeared the famous " new star M of 
1891. 



THE STARS OF WINTER. 49 

Perseus. To the right of Auriga and further 
along the stream of the Galaxy, which here 
becomes more brilliant, is the well-known 
constellation Perseus. This group, one of the 
most fascinating in the entire heavens to the 
beginner, is very easily identified. Its most 
notable feature is a triangle, almost equilateral, 
consisting of three stars, Alpha and Beta of 
the second magnitude, 

and Epsilon of the third. # 

Almost in the centre of # A 

this triangle but nearer Y 

to Epsilon is a fainter m # *\ 

star Nu, of the fourth ^ * 
magnitude. Between ** 

Alpha and Beta and ^ 

shghtly above the line 

joining them is Kappa, 
also of the fourth mag- 
nitude. ^ . 

Alpha Persei is the k , 

r hiG. 5. Perseus. 

brightest orb in a stream 

of stars, which forms the second distinguishing 
feature of the constellation. In order, and 
beginning from the highest point of the stream, 
the stars are Eta, of the fourth magnitude, 
Gamma, of the third, Alpha of the second, 
Psi of the fifth, Delta of the third. Here the 
stream curves sharply round, the stars in the 
curve being 48 Persei, Mu and Lambda of the- 

(2,015) 4 



.50 PEACTICAL ASTEONOMY. 

fourth magnitude, and 43 Persei of the fifth. 
The only other notable star in the constellation 
is Zeta, of the third magnitude, a somewhat 
isolated star, considerably below Epsilon. 

There are three chief objects of interest in 
the constellation Perseus to the ordinary 
observer with the unaided eye or binocular. 
These are Beta Persei or Algol, the famous 
variable ; the region surrounding Alpha Persei, 
or Mirfak ; and the double cluster near to the 
star Chi Persei. 

The name " Algol " is Arabic for " the 
demon " ; and from this some astronomers 
have assumed that the old Arab astronomers 
were acquainted with the variations in its 
light. Be this as it may, the fact that the 
star is variable was not discovered until com- 
paratively modern times, although the varia- 
tions are quite easy to follow with the unaided 
eye. Probably the reason of this is that the 
normal appearance of Algol is that of an ordi- 
nary star of the second magnitude. As Mr. 
J. E. Gore remarks : " Shining with a steady 
light for about 59 hours its lustre suddenly 
begins to diminish, and in about 4|- hours its 
brilliancy is reduced to about one-third of its 
normal brightness. It remains at its faintest 
for about 15 minutes, and then in about 
5|- hours recovers its former lustre." The 
variability of the star was discovered in 1669 



THE STARS OF WINTER. 51 

by Montanari, an Italian, and again in 1782 
by Goodricke, a young English astronomer, 
who accurately determined the period, which 
is 2 days, 20 hours, 45 minutes, 55 seconds. 
Goodricke was the first to suggest that the loss 
of light was due to partial eclipse of Algol 
by a large satellite, dark, or almost dark. 
This theory was confirmed twenty years ago 
by the late Professor Vogel of Potsdam, by 
means of what is known as Doppler's principle 
in spectroscopic observations. Vogel applied 
the principle to the observation of Algol, and 
he found that before each eclipse Algol was 
retreating from the Solar System, while after 
each eclipse it showed signs of approach. This 
proved conclusively that both Algol and its 
invisible companion -star were in revolution 
round their common centre of gravity, and 
that Algol was not inherently a variable, but 
merely a double star. Vogel also ascertained 
that in all probability Algol is a star about 
one million miles in diameter, and the satellite 
star about eight hundred thousand miles 
about equal in size to our sun the distance 
between the centres of the two stars being 
about three millions of miles. The presence 
of a third member of this remarkable system 
has often been suspected, although not yet 
confirmed. To the unaided eye Algol appears 
only a very ordinary star, with no outstanding 



52 PEACTICAL ASTKONOMY. 

features ; and it is remarkable that it was an 
amateur who discovered its variations, deter- 
mined its period, and put forward the true 
theory of its variations. 

Alpha Persei or Mirfak is the centre of a 
remarkable region of the heavens. When we 
observe this region with the binocular, we 
cannot but be impressed with its magnificence. 
There is a festoon of stars round Mirfak, 
arranged so symmetrically as to preclude the 
idea of a chance scattering. 

Above Eta and near to the borders of 
Cassiopeia is the star Chi Persei. Near to 
this star is the magnificent double cluster 
in Perseus. It is visible to the unaided eye 
as a hazy spot of misty light. A field- 
glass shows it much more plainly ; and even 
in a small telescope it is a striking spec- 
tacle, while in a large instrument it is awe- 
inspiring. 

Perseus is notable in astronomical history 
as the constellation in which the famous tem- 
porary star of 1901 " the new star of the 
new century " appeared. This star was dis- 
covered by the Rev. Dr. Anderson of Edinburgh 
in February 1901. At its maximum it sur- 
passed Capella in brilliance, and indeed it was 
one of the most brilliant temporary stars ever 
recorded. 

We have briefly surveyed the chief con- 



THE STAES OF WINTEK. 53 

stellations visible in the winter skies and have 
noted their chief stars and the most interesting 
binocular fields. Taking Orion as a starting 
point, the beginner is enabled to identify the 
other groups. After all the others have been 
identified, Orion still remains the chief attrac- 
tion. As a recent American writer has re- 
marked : "I have never beheld the first 
indications of the rising of Orion without a 
peculiar feeling of awakened expectation like 
that of one who sees the curtain rise upon a 
drama of absorbing interest. And certainly 
the magnificent company of the winter con- 
stellations of which Orion is the chief make 
their entrance upon the scene in a manner 
that may be described as almost dramatic. " 
It must not be forgotten that, although the 
winter stars may be seen and identified in and 
near to cities, they are seen under their most 
favourable conditions in the country districts 
where the air is clear and pure. As the same 
writer has expressed it : "In the pure frosty 
air the stars seem splintered and multiplied 
indefinitely, and the brighter ones shine with 
a splendour of light and colour unknown to 
the denizen of the smoky city whose eyes are 
dulled and blinded by the blaze of street lights. 
There one may detect the delicate shade of 
green that links in the imperial blaze of Sirius, 
the beautiful rose-red light of Aldebaran, the 



54 PRACTICAL ASTRONOMY. 

rich orange hue of Betelgeux, the blue- white 
radiance of Rigel, and the pearly lustre of 
Capella." 



CHAPTER IV. 

THE STARS OF SPRING. 

To the lover of nature the early spring is 
always a time of joy and hope ; to the lover 
of nature who is also a lover of celestial scenery, 
this feeling is tempered by one of regret that 
the brilliant constellations of the winter-time 
have disappeared from view, for this is the 
season described by Tennyson as the time 

" When the shining daffodil dies and the charioteer 
And starry Gemini hang like glorious crowns 
O'er Orion's grave low down in the west." 

Leo. The stars of spring seem very faint in 
comparison with their predecessors of winter. 
Not only are the stars of spring less brilliant ; 
they are also more sparsely scattered. To the 
observer who is anxious to become familiar 
with the constellations visible at this time 
there is one great drawback : there is not 
among the spring star-groups a constellation 
so brilliant and notable as Orion among those 
of winter. There is, however, a group which 
is not readily mistaken and whose outline is 



THE STARS OF SPRING. 55 

easily kept in mind. This is Leo the 
Lion the fifth of the constellations of the 
Zodiac. 

Leo may be easily found by means of the 
stars of the Plough. A line drawn from 
Alpha Ursae Ma j oris one of the " pointers " 
through Lambda and Mu Ursae Majoris. 
directs the observer to the stars of Leo. Per- 
haps, however, the constellation may be rec- 
ognised without this aid. Even the most 



. 



Fig. 6. Leo. 

casual star-gazer, casting a glance upward on 
any evening of spring, can hardly fail to 
notice a striking group of stars, east of the 
meridian, west of the meridian, or on the 
meridian itself, according to the hour of the 
night or the earliness or lateness of the sea- 
son. The constellation consists of two parts 
on the right-hand side a curve of stars known 
as " the sickle " from its resemblance to the 
implement of that name, and on the left-hand 
side a group of stars in the form of a triangle. 



56 PKACTICAL ASTRONOMY. 

Between the two parts of the constellation 
there is a gap, filled by faint stars. 

There are six principal stars in " the sickle " ; 
and the star at the bottom at once attracts 
attention. It is Regulus or Alpha Leonis, 
one of the fainter stars of the first magnitude. 
The position of the Sun at the summer solstice 
was in this group when the zodiacal constella- 
tions were first arranged, and this gave to 
Leo and its chief star a primacy not warranted 
by the actual importance of constellation or 
star. Mr. Maunder has shown this very 
clearly in his discussion of Leo in Astronomy 
without a Telescope : " Our present name for 
the star," he says, " is the variant proposed 
by Copernicus, for the older Latin Rex. 
Ptolemy calls it ' Basilikus,' the Arabs give 
it ' Malikiyy,' ' the kingly ' star, and the 
cuneiform inscriptions of the Euphratean 
valley refer to it as the ' star of the king,' 
whilst in ancient Persia it was the chief of the 
four royal stars. It is its place, however, and 
not its brilliance which has gained for Regulus 
this distinction, for almost all the first magni- 
tude stars are its superiors in brilliance." 

The next star of the curve is Eta Leonis, of 
the third magnitude. Above Eta, next in 
the curve, is Gamma, of the second magnitude. 
It is a double star visible in the telescope, and 
a favourite object for double-star observers. 



THE STAKS OF SPKING. 57 

The next star in the line is Zeta, of the third 
magnitude. At the summit of the curve 
the handle of the sickle is Mu, of the fourth 
magnitude ; while below Mu is Epsilon, of 
the third. In a line with Epsilon to the 
right-hand side is a fifth magnitude star, 
Lambda Leonis. 

A little south-west of Zeta is a point in the 
heavens, unmarked by any bright star, which 
has attracted the attention of astronomers for 
many years. There is a famous shower of 
meteors or falling stars known as the November 
meteors. It was discovered early in the last 
century that this shower was an annual one, 
generally unnoticed by the casual observer, 
but that every thirty-three or thirty-four 
years it became a magnificent spectacle. The 
paths of the meteors, traced backwards in 
the sky, were found to converge at the point 
near Zeta Leonis mentioned above. Hence 
the meteors were named " the Leonids." The 
shower is much less notable now than in former 
years, but November never passes without the 
appearance of a few meteors radiating from 
Leo. It is unnecessary to point out that the 
shower is caused by the Earth ploughing ite 
way through the shoal of minute bodies known 
as meteors, and that the meteors merely ap- 
pear to come from a point which lies in the 
same line of sight as the constellation Leo. 



58 PRACTICAL ASTRONOMY. 

Between the Sickle on the right-hand side 
of the constellation and the triangle on the 
left-hand side there is a dearth of bright stars. 
On the left hand of the figure we notice the 
three stars, Delta, Theta and Beta, which form 
a right-angled triangle, of which Theta marks 
the right angle. Beta is of the second magni- 
tude and is often spoken of by its Arabic 
name " Denebola." Theta is of the third 
magnitude and Delta of the second. Beta is 
an interesting object in a field-glass, as there 
are several fainter stars surrounding it. 

Virgo. Next to Leo, Virgo the Virgin 
is the most prominent constellation visible 
in spring-time. Virgo is the large star-group 
to the left-hand side of Leo and lower in the 
sky. It is easily identified, its figure resem- 
bling a large capital Y lying on its side. The 
stem of the Y is marked by two stars, Alpha 
Virginis (Spica) and Gamma. The latter 
star with Eta and Beta forms the right arm 
of the figure, and with Delta and Epsilon forms 
the left arm. The comparative brightness of 
the stars in Virgo and the dearth of other 
bright stars near renders the constellation 
very conspicuous. 

Beginning at the foot of the Y, Spica or 
Alpha Virginis is the brightest star of the 
constellation. It is of the first magnitude 
and of a bluish-white colour. There is nothing 



THE STARS OF SPRING. 59 

particularly remarkable about the appearance 
of Spica to the unaided eye, except its bright- 
ness. The remarkable fact concerning it is 
that it is a very close double star, so close as 
to be invisible in the telescope. By means of 
the spectroscope, however, we know that the 
bright star has a dark or nearly dark satellite 
star. The two stars, which are separated by 
only six and a half millions of miles, revolve 

c 



r 



Fig. 7. Virgo. 

round their common centre of gravity in about 
four days, with a velocity of fifty-seven miles 
a second ; and the joint mass of the two stars 
is two and a half times that of the sun. It is 
obvious that in this system we have an arrange- 
ment quite different from that in the Solar 
System. The equality in size of the two stars 
makes it impossible for the one to revolve 
round the other. Both revolve round their 
common centre of gravity. 



60 PEACTICAL ASTRONOMY. 

Proceeding up the stem of the Y we reach 
Gamma Virginis, of the third magnitude. It 
is a famous double star, but of course far 
beyond the reach of the binocular. It may 
be seen with telescopes of 3 and 4 inches in 
aperture. The fainter star requires 185 years 
to complete its revolution. Here then we 
have a double star of exactly opposite type 
from Spica. 

The four stars which, along with Gamma, 
form the two arms of the Y, are all of the 
third magnitude and do not call for particular 
attention. It is interesting to note that in 
the region of the sky between the arms of the 
Y and Beta Leonis, is the point known as the 
pole of the Galaxy. That is to say, this 
region of the heavens is farthest from the 
Milky Way. If we liken the starry sphere to 
an immense globe and the Galaxy to the 
equator of that globe, this particular region 
contains its northern pole. In tnis region of 
the sky the stars are most sparsely scattered. 

Corvus and Crater. The sky below Virgo 
and Leo is divided between two insignificant 
constellations Corvus, the Crow, and Crater, 
the Cup. 

Corvus may be recognised by the trapezium 
formed by its four chief stars, Delta at the 
north-eastern corner, Gamma at the north- 
western, Epsilon at the south-western, and 



THE STARS OF SPRING. 61 

Beta at the south-eastern. Delta, Gamma, 
Beta and Epsilon are of about the third mag- 
nitude. Near to Delta is Eta, of the fifth 
magnitude ; and below Epsilon is Alpha, of 
the fourth magnitude. Crater is a less notable 
group. The only noticeable stars are Delta 
of the third magnitude, Gamma of the fourth, 
and Alpha of the fourth. These three stars 
form a triangle. 

Hydra and Cancer. On the south and west 
of these constellations is the long straggling 
group known as Hydra, the longest con- 
stellation in the heavens, and one of the most 
difficult to identify. Its most brilliant star 
is Alpha Hydrae, known by its Arabic name 
of "Al Fard" the "solitary" the name 
possibly being suggested by the barrenness 
of the adjacent portions of the sky. Al Fard 
is a reddish star of the second magnitude and 
from its colour was named by the ancient 
Chinese astronomers " the red bird." Al 
Fard is really the only notable star in Hydra, 
which winds from the borders of Libra to the 
borders of Cancer. This notable though faint 
constellation may easily be found by means of 
the most northern stars of Hydra. These 
stars marking the head of the monster are 
above Al Fard, on the right-hand side. Di- 
rectly above these stars and between Gemini 
and Leo, is the little group of Cancer, the Crab. 



62 PRACTICAL ASTRONOMY. 

Insignificant though Cancer appears, it is the 
fourth of the zodiacal constellations. The 
stars Gamma, Delta, Zeta and Mu form a 
quadrilateral ; while Delta and Mu, the two 
lowest stars of the quadrilateral, form a trape- 
zium with Alpha and Beta. The most notable 
feature in the constellation is, however, the 
cluster " Praesepe," or the " Bee-Hive." This 
is visible to the unaided eye as a hazy cloud- 
like object between the two fourth-magnitude 
stars Gamma and Delta Cancri. Next to the 
Pleiades, this is the most conspicuous star- 
cluster in the heavens. It was noted by the 
ancient astronomers, who, however, failed to 
detect the individual stars and classified it as 
a " nebula " or little cloud this being the first 
occasion on which this term was applied to a 
celestial object. Praesepe is a striking object 
in a binocular and in a small telescope, although 
much less noticeable than the Pleiades. 

Two other insignificant groups may be noted 
among the spring constellations. Above Virgo 
and on the left-hand side of Leo is the constella- 
tion of Coma Berenices, which although not one 
of the original constellations named in pre- 
historic times is yet very ancient. The name 
signifies the " hair of Berenice," Queen of 
Egypt. This princess the story goes vowed 
her hair to the gods if her husband returned 
safely from a war in which he was engaged. 



THE STAES OF SPKING. 63 

Her hair was stolen from the temple in which 
it had been placed after her husband's return, 
whereupon the royal astronomer of the day 
declared it had been translated to the celestial 
regions, and pointed to the shimmering star- 
group as proof of the truth of his assertion. 
The constellation, while destitute of bright 
stars, possesses a number of faint ones and is 
an interesting field for the binocular. 

Above Leo and Virgo and below the Plough 
is another insignificant constellation, Canes 
Venatici, the " Hunting Dogs." This con- 
stellation, indeed, is almost circumpolar, but 
is at its best position for observation in 
spring. There is only one bright star, desig- 
nated Alpha, which is easily found when the 
Plough is known ; for it is the next bright star 
to Eta Ursae Majoris, the last star of the handle 
of the Plough. It is also known by the some- 
what ludicrous name of Cor Caroli, " Charles's 
Heart." It was so named because it was 
believed by the Royalists to have shone with 
exceptional brilliance on the evening before 
Charles II. made his entry into London for 
the first time after the Restoration. There 
are no other bright stars in the constellation. 
To the telescopic astronomer it is chiefly fa- 
mous on account of the famous spiral nebula. 
This magnificent object, however, is far beyond 
the reach of the unaided eye or binocular. 



64 PEACTICAL ASTRONOMY. 

The constellations Bootes and Corona Bore- 
alis are by some astronomers included among 
the stars of spring ; but it is more correct to 
include them among the summer stars. They 
are certainly visible in spring-time, but they 
are most prominent of all in the short summer 
nights. Therefore in this work they will be 
described among the summer stars in the 
next chapter. 

The average observer of the heavens cannot 
fail to be impressed with the scarcity of bright 
stars in spring-time. In the winter skies, 
described in the last chapter, no less than 
seven stars of the first magnitude are visible 
Sirius, Betelgeux, Rigel, Procyon, Aldebaran, 
Capella and Pollux, along with a large number 
of bright stars of the second magnitude. On 
the other hand, Regulus and Spica are the 
only first-magnitude stars among the spring 
constellations proper. Not only are there 
few bright stars in spring, but as compared 
with other seasons of the year there is a 
remarkable dearth of stars of all magnitudes. 
The reason of this is not far to seek, and al- 
though its consideration leads into the higher 
problems of astronomy, it may be mentioned 
here. 

As was seen in a previous chapter, the Milky 
Way or Galaxy is the ground-plan of the 
Universe. It is itself an agglomeration of 



THE STARS OF SPRING. 65 

many millions of stars, individually invisible 
to the unaided eye, which are seen collectively 
as a belt of misty light. t Not only is the 
Galaxy an agglomeration of faint stars, but it 
is a region of the heavens in which the bright 
stars are most thickly scattered. The late 
Mr. Gore, one of the ablest of non-professional 
astronomers, examined the positions of all 
the bright stars on the northern hemisphere. 
He found that, of thirty-two stars brighter 
than the second magnitude twelve lie on the 
Milky Way or on faint nebulous light con- 
nected with it ; and of those brighter than 
the third magnitude thirty-three stars out of 
ninety-nine lie on the Galaxy. Thus, the 
number of brighter stars is considerably more 
than that due to the area of the Galaxy. In 
summer, autumn, and winter, we see the 
Milky Way more favourably than in spring. 
At this season of the year the part of the 
heavens exposed chiefly to our view is the 
region near to and round about the pole of the 
Galaxy. The stars increase in density from 
the pole of the Galaxy to the Galaxy itself ; 
therefore the region round about Leo, Virgo, 
and Hydra is naturally the least rich region 
of the heavens. 

This is the explanation of the relative 
paucity of stars in the skies of spring. In 
summer, although owing to the length of day- 

(2,015) 5 



66 PEACTICAL ASTRONOMY. 

light we see less of the starry heavens than in 
spring, richer and more crowded regions come 
into view. These will be considered in the 
next chapter. 

CHAPTER V. 

THE STARS OF SUMMER. 

" In the soft air of a summer night," says 
an American astronomer, "when fireflies are 
flashing their lanterns over the fields, the stars 
do not sparkle and blaze like those that pierce 
the frosty skies of winter. The light of Sirius, 
Aldebaran, Rigel and other midwinter bril- 
liants, possesses a certain gem-like hardness 
and cutting quality, but Antares and Vega, 
the great summer stars, and Arcturus, when 
he hangs westering in a July night, exhibit a 
milder radiance, harmonising with the char- 
acter of the season." This description is true 
to nature : the light of the summer stars is 
different from those of winter, but the differ- 
ence is chiefly atmospheric ; there is no pecu- 
liar quality in the light of the various stars 
which are visible in summer-time. 

The chief drawback to the study of the 
constellations in summer is the fact that the 
period of actual darkness is so brief. The 
summer stars, in short, are not so obvious as 



THE STARS OF SUMMER. 67 

those of winter. They do not intrude them- 
selves on the view of the observer ; it is neces- 
sary for him to look for them. They are none 
the less interesting on this account ; there is 
indeed a certain charm in watching the summer 
sky darkening as midnight approaches and the 
shy stars peeping out one by one in the heavens. 

But the student of the 

p 

summer skies must be en- 
thusiastic. His interest in 
the heavens must be first % b 
stimulated by observation 
of the constellations which 
dominate the skies of ^ 
winter and spring respec- 
tively. 

Bootes. The chief con- 
stellation of the summer . 
skies is identified by its * 7 
principal star, Arcturus. 
This star is very easily ^ JB . 8 ^ BooleB . 
recognised. A line drawn 
from Eta Ursae Ma j oris, the last star in the 
handle of the Plough, will reach Arcturus. 
This is one method of finding the star ; but 
Arcturus is so obvious that it will attract 
the attention of the most casual observer. 
But for the presence of this brilliant star the 
constellation Bootes would be in no way re- 
markable. At the top of the constellation 



68 PRACTICAL ASTRONOMY. 

is a triangle formed by three stars Beta, 
Gamma and Delta. Delta, at the left-hand 
corner of the triangle, is almost in a straight 
line with Epsilon Bootis and Arcturus ; while 
Arcturus itself forms a triangle with other two 
fainter stars Eta and Zeta. The figure of 
Bootes is one not easily remembered, and al- 
though the method of remembering the stars 
by means of lines and triangles has, speaking 
generally, many drawbacks, in the case of 
Bootes it is the only method practicable. 

Arcturus, or Alpha Bootis, is one of the most 
brilliant stars in the heavens. The majority 
of astronomers consider Arcturus to be slightly 
more brilliant than Vega and Capella ; but 
there is not unanimity on this point, for the 
three stars are of different colours, Vega being 
bluish-white, Capella bright yellow, and Arc- 
turus a deeper yellow, shading into orange. 
It is therefore difficult to determine the minute 
differences in magnitude ; yet the majority 
of astronomers believe Arcturus to be the 
brightest of the three. It is therefore the 
most brilliant star north of the celestial equator, 
and with the exception of Sirius, the brightest 
star visible to observers in the northern hemi- 
sphere. 

Arcturus, which is situated at an enormous 
distance from the Solar System, appears to be 
a star of gigantic size. Dr. Elkin, an American 



THE STARS OF SUMMER. 69 

astronomer, made an attempt to measure the 
distance of Arcturus. He found that the 
star's displacement, due to the change in the 
observer's position, when he is at exactly op- 
posite points of the Earth's orbit in January 
and July respectively, for instance is about 
equal to the apparent distance between the 
heads of two pins placed an inch apart and 
viewed from a distance of about 180 miles. 
The distance deduced from Dr. Elkin's meas- 
urement is of course by no means beyond 
doubt ; but assuming that the estimate is 
fairly near the truth, Mr. Garret P. Serviss, 
an American astronomer, has calculated that 
if the Earth were situated midway between the 
Sun and Arcturus it would receive over 5000 
times as much light from the star as from the 
Sun ; and assuming that the radiation of the 
star is the same per unit of surface as the Sun, 
he finds that Arcturus exceeds the Sun in 
volume by about 375,000 times. 

Of the other bright stars in the constellation, 
Epsilon is of the second magnitude, Eta, Zeta, 
Gamma and Delta of the third, and Beta and 
Mu of the fourth. 

Mr. Maunder compares Bootes to Orion, 
remarking that when Arcturus is excluded, 
" the principal remaining stars of the con- 
stellation make up a representation, pale and 
distorted, it is true, but a representation for all 



70 PKACTICAL ASTRONOMY. 

that of the most glorious constellation in the 
sky." This idea may assist the observer in 
tracing the shape of Bootes. 

Corona Borealis. To the left of Bootes is 
a constellation which although small is very 
conspicuous Corona Borealis, or the Northern 
Crown. The group is shaped exactly like a 
coronet, and, as it really resembles the object 
after which it is named, it is easily identified 
and as easily remembered. There are six 
chief stars in the constellation. Beginning at 
the right-hand side, the stars are in order 
Theta, Beta, Alpha, Gamma, Delta and Ep- 
silon. Alpha is of the second magnitude and 
the others of the fourth. 

In this constellation, in 1866, appeared the 
famous temporary star known as " the blaze 
star." It was discovered by an Irish amateur 
astronomer who, on casting a glance round 
the skies, saw the familiar configuration of 
Corona Borealis completely altered by the 
presence of a brilliant stranger. Four hours 
earlier it was not visible ; in a few hours 
some mighty conflagration had taken place, 
which caused the star to shine with at least 
nine times its former brilliancy ; for it is 
believed that it was known as a minute tele- 
scopic object before the outburst. 

East of Bootes and Corona Borealis is a 
region of the heavens which is probably one 



THE STAKS OF SUMMER. 71 

of the most difficult for the observer to know 
thoroughly. As our glance travels eastward 
along the heavens we reach richer regions 
where the stars are more profusely scattered ; 
for we are again approaching the vicinity of 
the Milky Way, one of the branches of which 
passes through Ophiuchus and Serpens. The 
stars are not grouped in easily remembered 
figures, nor are the constellations themselves 
marked off one from the other. Serpens and 
Ophiuchus, for instance, intersect in a manner 
which is very puzzling to the beginner in 
constellation study. The key to this inter- 
section is found in the names of the star-groups 
themselves. " Serpens " is Latin for " the 
Serpent " while " Ophiuchus " is " the Serpent- 
bearer." On the old globes in which the 
mythical figures are represented, Ophiuchus 
the serpent-bearer is represented as engaged 
in a life-and-death struggle with the serpent 
which is coiled round him. The natural 
grouping of the stars has in this case been ig- 
nored for the purpose of representing the old 
fable in the sky, with the result that it is 
very difficult for the beginner to recognise 
which stars belong to Serpens and which to 
Ophiuchus. Above these two groups is 
Hercules, which, although not a striking con- 
stellation, is much easier to follow. 

Hercules. On the left of Corona Borealis 



72 PRACTICAL ASTRONOMY. 

and somewhat higher in the sky than that 
constellation, our attention is attracted by 
four stars which form a quadrilateral which is 
almost a square. These four stars are Pi of 
Hercules, on the top left-hand corner, Eta on 
the top right-hand corner, Zeta on the bottom 
right-hand, and Epsilon on the bottom left- 
hand. All four are of the third magnitude. 
Close to Pi is Rho, of the fourth magnitude, 
while on a straight line from Eta to Zeta, but 
considerably nearer to the former star, is the 
famous star-cluster in Hercules. This wonder- 
ful celestial spectacle is beyond the reach of 
the unaided eye, but it may be noticed if looked 
for with the binocular and seen fairly well 
with a small telescope. Larger instruments 
have shown it to be one of the most wonderful 
objects in the entire heavens containing many 
thousands of stars. For many years it was 
believed that the cluster represented a mere 
local aggregation of stars, but our whole con- 
ception of its place in the Universe has been 
revolutionised by a remarkable investigation 
carried through within the last few years by 
a distinguished American astronomer, Dr. 
Harlow Shapley. From an exhaustive study 
of the colours and absolute maguitudes of the 
stars in the cluster Dr. Shapley reached the 
conclusion that it is situated at a distance so 
great that light requires 100,000 years to 



THE STARS OF SUMMER. 73 

travel from the cluster to our system, and 
1100 years to cross from one side of the cluster 
to the other. In fact, the cluster is possibly 
an " island universe," though considerably 
smaller in extent and perhaps not altogether 
independent of our Galaxy. That it is analo- 
gous in its nature is shown by the recent work 
of Dr. Sbapley, who has detected the presence of 
a zone of galactic concentration in the cluster, 
similiar to the Milky Way. Professor Edding- 
ton has truly remarked that " were we trans- 
planted into the midst of the great Hercules 
cluster our knowledge of its constitution could 
scarcely be so precise as that which Mr. Shapley 
has discovered at a distance of 100,000 light 
years ; and the labour would have been in- 
comparably greater." 

Thus when we observe the cluster it is well to 
realise that we are looking far beyond the limits 
of the Stellar System into vistas of infinity. 

From the quadrilateral in Hercules the other 
stars of the constellation may be found. Al- 
most directly below Zeta is Beta, of the 
second magnitude, the space between Zeta 
and Beta being a little greater than that 
between Zeta and Eta. Close to Beta, but 
slightly lower in the sky, is Gamma, between 
the third and the fourth magnitude. To the 
left of the quadrilateral is a portion of the 
heavens in which it seems at first very difficult 



74 PRACTICAL ASTRONOMY. 

to discern any order in the scattered stars. 
There is, however, a curve of stars which may 
be remembered. Beginning with Beta after 
a considerable space we come to Delta, of the 
third magnitude. As far from Lambda as 
Lambda is from Delta, we come to Mu, of the 
third magnitude. The curve turns more sharply, 
and we reach Xi and Nu, two fourth-magnitude 
stars comparatively close together. Again 
there is a considerable gap and we reach Theta, 
also of the fourth magnitude, which is almost 
in a straight line with three stars so that the 
curve becomes practically straight. These are 
a fifth-magnitude star marked 90 Herculis, Iota 
of the third magnitude, and Beta Draconis of 
equal brightness. In fact Iota Herculis is 
naturally one of the four stars forming the 
notable diamond-shaped figure in Draco the 
other three being Xi, Beta and Gamma Dra- 
conis. 

Ophiuchus and Serpens. Alpha Herculis, a 
bright reddish star, irregularly variable, may 
be found almost directly below Delta a con- 
siderable stretch of sky intervening. Close to 
this star is Alpha Ophiuchi. So close indeed 
are the two stars that Alpha Herculis seems to 
belong more naturally to Ophiuchus than to 
Hercules. Below Alpha Ophiuchi, a second- 
magnitude star, is Beta of the third magnitude ; 
and again below this star, although not in a 



THE STAES OF SUMMER 75 

straight line but in a line slanting to the left, 
is Gamma, of the third magnitude. We may 
note that in this constellation appeared the 
famous new star of 1604. In this same group, 
too, is situated a faint star with a very large 
" proper motion," discovered by Professor 
Barnard of the Yerkes Observatory in 1916. 
This faint star is situated at a distance which 
light requires a little over six years to traverse. 
It is with the single exception of Alpha Cen- 
tauri our nearest known stellar neighbour. 
Obviously, it must be one of the smallest and 
faintest of the stars. 

We may now direct our attention to Serpens, 
which begins below Corona Borealis in the 
space between Hercules and Bootes. A wind- 
ing stream of stars may be traced from near 
the boundaries of Hercules Kappa Serpentis 
of the fourth magnitude, Beta of the third, 
Delta of the third, Alpha of the second (near 
to which is Lambda of the fourth), Epsilon 
of the third, and after a considerable gap 
Delta, Epsilon and Zeta of Ophiuchus. It is 
almost impossible to remember these stars 
from any figure or grouping. They must be 
followed star by star, and it is fortunate for 
the observer that they generally run in lines 
and streams. There are some magnificent 
binocular fields in Serpens, which is well worthy 
of careful attention. 



76 PEACTICAL ASTKONOMY. 

Lower down in the heavens are the three 
least-known constellations visible to north- 
ern observers Libra, Scorpio and Sagittarius. 
These, which are zodiacal constellations, only 
rise a short distance above the horizon ; and 
as their period of visibility is in summer-time, 
when the evenings are so long clear and the 
period of darkness is brief, these star-groups 
are among the least known in the heavens. 

Libra. Libra, or the Scales, the seventh 
constellation of the Zodiac, lies east of Virgo 
and considerably lower in the heavens. Alpha, 
Delta and Beta form a triangle. Alpha is 
almost exactly on the ecliptic, the line which 
marks the Sun's apparent path in the heavens. 
In the field-glass this star is a beautiful double. 
Beta is of a greenish hue. This star is believed 
to have decreased in magnitude within the 
last two thousand years. It is now of the 
second magnitude ; whereas Ptolemy cata- 
logued it as a star of the first magnitude. 

Scorpio. Next to Libra, but more conspic- 
uous although lower in the sky, is Scorpio 
the Scorpion the eighth constellation of the 
Zodiac, or rather the part of Scorpio which is 
visible to observers in our northern latitudes. 
In more southern latitudes Scorpio is one of 
the most magnificient constellations in the 
heavens ; it is not only rich in stars but it is 
immersed in one of the most brilliant portions 



THE STARS OF SUMMER. 77 

of the Milky Way. The star Xi of Scorpio, 
which is on a line with Mu Serpentis, is the 
first of the curve of stars which distinguish the 
northern portion of the star-group. Below Xi 
lies Nu, and from Nu the curve includes Beta, 
Delta, Sigma, Alpha and Tau. Alpha, better 
known by its Greek name of Antares, is a star 






Fig. 9. Scorpio. 

of the first magnitude. It is of a fiery red 
colour, hence its name of " Ant- Ares," the rival 
of Ares or Mars. It is a star of the same 
spectral type as Betelgeux in Orion. When 
observed with a good telescope it is seen to be 
a double star, the little satellite-orb being of a 
greenish colour. For many years these colours 
red and green were thought to be the effect 



78 PKACTICAL ASTRONOMY. 

of contrast, but the spectroscope has shown 
that the colours are real. 

The constellation is full of interesting and 
beautiful fields even for an opera-glass ; and if 
Scorpio were seen in winter, spring or autumn, 
it would probably be one of the most familiar 
and most thoroughly explored of star-groups ; 
but its slight elevation above the horizon and the 
fact that it is only seen in the summer months 
render it less interesting to the beginner than 
its brilliance and importance warrants. 

Sagittarius. The ninth constellation of the 
Zodiac, Sagittarius the Archer, lies to the 
left-hand side of Scorpio, but slightly higher 
in the heavens. Although more elevated, 
however, it is less brilliant than Scorpio and 
possibly less familiar ; while it is certainly less 
easy to follow. It is chiefly notable for the 
presence of the Milky Way, which is here very 
brilliant ; and in the evenings of late summer, 
this part of the Galaxy, low down in the south- 
west, shines with a strange brilliance. The 
chief stars of Sagittarius visible to northern 
observers included in a curve which begins 
near the borders of Ophiuchus are Mu, 
Lambda, Delta and Epsilon, the three latter 
being set in the stream of the Milky Way. 
In the southern parts of Sagittarius the Milky 
Way divides into two branches, one branch 
running into Scorpio and Ophiuchus and the 



THE STARS OF SUMMER. 79 

other running straight through Sagittarius into 
Aquila. 

Lyra. This star-group cannot be mistaken. 
It lies to the left of Hercules and to the right 
of the stream of the Galaxy. Its most dis- 
tinguishing feature is its brightest star, Vega 
or Alpha Lyrae. In the chapter on the 
northern stars, reference has been made to 
Vega, which like Capella is a circumpolar star, 
and which occupies the position in summer 
which Capella holds in winter, being high in 
the sky. Vega, whose light is of a bluish-white 
tinge, is one of the most brilliant stars in the 
sky. It appears to be situated at an immense 
distance from the Solar System, and to be a 
star of about three or four times the light- 
giving power of Sirius, which considerably out- 
shines our Sun. 

The configuration of Lyra is easily remem- 
bered. On the left of Vega are three stars 
of the fourth magnitude, Epsilon, Zeta and 
Delta, and two of these, Epsilon and Zeta, 
form with Vega an equilateral triangle. Be- 
low Vega are Beta and Gamma Lyrae, both 
of the third magnitude, which form a quadri- 
lateral with Delta and Zeta. These are the 
chief stars of the constellation. 

Of these stars Beta is notable as a famous 
variable star, the variations of which are easily 
within reach of the unaided eye. It varies 



80 PRACTICAL ASTRONOMY. 

from the third to the fourth magnitude in 12 
days 21 hours 47 minutes. The variations of 
this star are believed to be due to the revolu- 
tion of two stars, one less brilliant than the 
other round their common centre of gravity. 
The stars, according to Newcomb, are of 
unequal size and almost in contact, and the 
smaller body is much brighter than the larger. 
The system thus revealed is certainly one of 
the most remarkable in the heavens. This 
variable star is a very suitable object for the 
observer who is commencing the study of 
variables, as its changes can all be followed 
by the unaided eye. 

Epsilon Lyrae is a double star, visible as 
such to keen eyesight. The binocular easily 
reveals the star as double, and a small tele- 
scope shows each of the two to be itself double ; 
so in Epsilon Lyrae we have a quadruple star. 
Perhaps, however, the most interesting star in 
the constellation is Delta Lyrae, not on account 
of the star itself, but on account of a point in 
the sky near it. The most reliable astronom- 
ical calculations have shown that the Sun, 
carrying with it the Earth and the planets, is 
travelling towards this portion of the heavens 
with a velocity of about eleven miles per 
second. As Sir Robert Ball has remarked : 
" The speed with which this motion of our 
system is urged is such as to bring us every 



THE STARS OF SUMMER. 81 

day about 700,000 miles nearer to this part 
of the sky. As you look at Delta Lyrae 
to-night, you may reflect that within the last 
twenty-four hours you have travelled towards 
it through a distance of nearly three-quarters 
of a million of miles. So great are the stellar 
distances that a period of not less than 180,000 
years would be required before our system, even 
moving at this impetuous speed, could traverse 
a distance equal to that by which we are 
separated from the nearest of the stars." The 
observer may be tempted to ask, when then 
shall we reach Delta Lyrae ? In all proba- 
bility we shall never reach it. For the star, 
like our own Sun, probably has its own motion, 
and even when our system in the course of 
thousands of thousands of years if it is then 
in existence does reach the place now occupied 
by Delta Lyrae, that star will be far away 
from its present position. As we contemplate 
the region of the heavens towards which we 
are moving, surrounding this little star, great 
thoughts of our world and its destiny arise in 
our minds. 

Some astronomers regard Cygnus and Aquila, 
the adjacent star-groups, as summer con- 
stellations ; but we shall consider them as 
autumn groups, because, although well seen 
in summer, they are seen in their full glory in 
the autumn season. 

(2,015) 6 



82 PRACTICAL ASTRONOMY. 

CHAPTER VI. 

THE STARS OF AUTUMN. 

In the calm clear skies of autumn the most 
notable feature on a moonless night is the 
majestic sweep of the Galaxy spanning the 
heavens like a great arch. In September and 
October the Milky Way is seen to its fullest 
advantage ; and in its course in this part of 
the heavens it passes through some of the 
most wonderful regions of the sky. At this 
season of the year it is easier to comprehend 
the true nature of the Milky Way than at 
others. As was mentioned previously, it is the 
ground-plan or equator of the entire Universe 
of stars ; the stars are there much more nu- 
merous than in other portions of the heavens. 
A number of observations with a telescope or 
even with a binocular is sufficient to show 
that this crowding of the stars towards the 
Galaxy is a fact. In a telescopic or binocular 
field, in this very region the observer may 
count as many as fifty or sixty stars ; while 
in an equal field in Virgo or on any part of the 
heavens, near to the galactic poles, he may 
count as few as five or six. The Galaxy is the 
fundamental reference plane of the entire Uni- 
verse, just as the equator is of the Earth. In 



THE STARS OF AUTUMN. 83 

this chapter we shall discuss the constellations 
of autumn, beginning with those on the 
Galaxy. 

Cygnus. Looking up to the heavens on 
an autumn evening, and glancing along the 
Galaxy, it is impossible to overlook what is, 
if not the most brilliant, perhaps the most 
interesting constellation in the entire heavens. 
Cygnus, the Swan, is immersed in one of the 
most brilliant parts of the Milky Way. It is 
situated to the left of Lyra, but it is so con- 
spicuous that no directions are required to find 
it. The constellation is shaped like a cross ; 
indeed so obvious is the cruciform shape that 
it has often been termed the " Northern 
Cross." At the centre of the cross is the star 
Gamma. The horizontal arm of the cross is 
marked by Epsilon, Gamma and Delta, be- 
ginning at the left-hand side. The perpendicu- 
lar arm is marked by Alpha, Gamma, Eta and 
Beta, beginning with the uppermost star, 
almost in a straight line. In addition there 
is another bright star, Zeta, not included in 
the cruciform figure. 

Of all constellations Cygnus includes the 
greatest variety of notable stars from the point 
of view of the observer with the unaided eye or 
binocular. Beginning with Gamma, the cen- 
tral star of the constellation, of the second 
magnitude, it is to be noted that it is the 



84 PRACTICAL ASTRONOMY. 

central star of a very wonderful region, being 
itself the last star of a curve or crown of 
stars. Alpha Cygni, also known by its Arabic 
name of Deneb, is one of the faintest stars of 
the first magnitude ; and the region surround- 
ing this star is even more striking than that 
round Gamma Cygni. The star is thickly 
immersed in the Galaxy and well repays ob- 
servation with the binocular. The boundary 



< # ! 

Fig. 10. Cygnus. 

between the galactic light and the darkness of 
the small rift in the Milky Way near the star 
is marked by a stream or line of stars which 
appears distinctly connected with the nebulous 
light of the Milky Way. 

With the aid of the binocular it is easy 
to find 61 Cygni, the second nearest star in the 
northern hemisphere. In a straight line from 
Alpha Cygni, parallel to the horizontal arm of 
the cross, we reach Nu, a star of the fourth 



THE STARS OF AUTUMN. 85 

magnitude. Prolonging the line not quite so 
far as the distance from Alpha to Nu, we 
reach a faint star of the fifth magnitude. This 
is the famous 61 Cygni, one of the nearest stars 
in the heavens. This star is distant from the 
Solar System 459,000 times the distance of the 
Earth from the Sun. Light requires about 
seven^years to reach the Earth from this star, 
which is thus much nearer to the Solar System 
than any of the most brilliant stars in the 
northern sky. Relatively to the Sun, it is a 
very small star. 

To the naked-eye observer, the brilliance 
of the Galaxy in Cygnus is very noticeable. 
There is a luminous spot north of Alpha, and 
between Beta and Gamma the galactic light 
is very brilliant. Perhaps, however, the most 
remarkable object in the constellation is the 
star Beta, of the third magnitude. A field- 
glass, or better still a small telescope, shows 
the star to be double, the large star, of the 
third magnitude, being topaz yellow and the 
smaller one sapphire blue. A view of this 
star is a never-to-be-forgotten spectacle. 

At the risk of a digression we may turn 
our attention briefly to the coloured stars, 
such as Beta Cygni, and to the conditions exist- 
ing on planets revolving round any of these 
stars. Proctor, in one of his books, discussed 
the scene visible from any planets situated 



86 PEACTICAL ASTRONOMY. 

thus. He supposed one of the stars to be blue 
and the other orange as is practically the 
case with Beta Cygni and the planet to be 
placed in the same position as the Earth in 
our system. There would be an endless variety 
of sights in the heavens. The blue and orange 
suns might rise together and produce " double 
day," or the blue sun might rise as the orange 
sun was setting and there would be no night. 
The clouds would present extraordinary ap- 
pearances, some parts shining blue, some parts 
orange, according to whichever sun happened 
to shine direct upon them. The case is of 
course hypothetical. It must be borne in 
mind that such systems must be completely 
different from the solar family. In our system 
we have one bright star holding sway over a 
number of planets. In these systems there 
are two suns, which may or may not have 
planets revolving round them. If such planets 
do exist, and there is no reason why they 
should not, they will certainly experience very 
varied sights in their skies. 

Aquila. Proceeding downwards along the 
stream of the Galaxy we come to the constella- 
tion Aquila, the Eagle. This constellation is 
easily recognised by its three chief stars Gamma, 
Alpha and Beta, close together and almost in a 
straight line. The same line prolonged down- 
wards reaches Theta. In a straight line 



THE STAKS OF AUTUMN. 87 

with Theta, pointing north-west, are other 
two stars, Eta and Delta. At the extreme 
north-western corner of the constellation are 
two stars Zeta and Epsilon ; and at the south- 
western extremity is Lambda. 

Of the stars in Aquila, Alpha is of the first 
magnitude, Gamma, Theta, Delta and Zeta of 
the third ; Beta between the third and the 
fourth, and Epsilon and Lambda of the fourth. 
Eta is a variable star, varying from the third 
magnitude to the fourth in 7 days 4 hours. 

Alpha Aquilae, better known by its Arabic 
name of Altair, stands midway between Beta 
and Gamma. It is a bright star of the first 
magnitude, of a bluish- white tint. It has been 
calculated that light requires about seventeen 
years to travel from Altair, and whether this 
calculation be correct or not, it is certainly 
nearer than many other stars of the first magni- 
tude. The Galaxy is very bright in Aquila, 
although scarcely so striking as in Cygnus. 
Lambda stands on a bright spot of milky 
light, which is known as Scutum Sobieskii 
" Sobieski's Shield." 

On June 8, 1918, a brilliant temporary star 
blazed out in Aquila, close to the boundary 
of Serpens. At maximum it surpassed Nova 
Persei, and was the most brilliant "Nova" 
since 1604. By September its light had de- 
creased to the fifth magnitude. As in the case 



88 PRACTICAL ASTRONOMY. 

of Nova Persei, Nova Aquilae was observed 
independently by a number of observers. 

Between Aquila and Cygnus are three in- 
significant little groups which scarcely deserve 
to be designated as constellations. Above the 
three stars, Gamma, Alpha and Beta is Sagitta, 
the Arrow, which contains no very remarkable 
objects and might well be included in Cygnus 
or Aquila. To the left and slightly lower in 
the heavens is Delphinus, the Dolphin, the 
most conspicuous of the three groups. It lies 
to the left of the Galaxy and is easily noted on 
a clear night. There are four stars arranged 
in the form of a trapezium, Alpha and Beta 
on the right, Gamma and Delta on the left. 
Beta is of the third magnitude and the other 
three of the fourth. Above Delphinus is Vul- 
pecula, the Fox. It contains no notable stars, 
and is generally disregarded by astronomers. 

Capricornus. Below Aquila and to the left 
of Sagittarius is Capricornus, the Goat, the 
tenth of the zodiacal constellations. The chief 
stars of Capricornus, Alpha and Beta, may 
be easily found exactly below Altair, much 
lower down in the heavens. The sky is much 
more barren here than in Aquila, for the Galaxy 
slopes away into Sagittarius and Scorpio. 

Alpha Capricorni, the uppermost of the two 
stars, is a double star, visible to the unaided 
eye, and well seen in a binocular. The two 



THE STARS OF AUTUMN. 89 

stars have no connection, and merely appear 
close together because they are in the same 
line of vision. Beta is also a double star, as 
seen in the binocular. Both Alpha and Beta 
are stars of the third magnitude. Almost in 
a line with Beta are the stars Theta, Iota and 
Gamma of the fourth magnitude, and Delta 
of the third. They are not, however, in any 
way notable. On the whole Capricornus is not 
a particularly interesting constellation to the 
observer either with the unaided eye or the 
binocular. 

Aquarius and Pisces. A similar remark ap- 
plies to Aquarius and Pisces, the eleventh 
and twelfth constellations of the Zodiac 
respectively. Aquarius fills a large part of 
the heavens, stretching from the boundaries of 
Aquila above Capricornus down to the horizon. 
Alpha Capricorni is almost in a straight line 
with Epsilon, Mu, Beta and Alpha Aquarii. 
Epsilon is of the fourth magnitude, Mu of the 
fifth, and Beta and Alpha of the third. Close 
to Alpha is a compact group of four stars, the 
most notable feature in the constellation 
Gamma, Zeta, and Eta almost, but not quite, 
in a straight line, and Pi above Zeta. Gamma 
and Zeta are of the third magnitude, Eta of 
the fourth and Pi of the fifth. Below this 
group is a quadrilateral, consisting of Lambda, 
Theta, Iota, and Delta. On a clear autumn 



90 PKACTICAL ASTKONOMY. 

evening a bright star is sometimes to be seen 
glimmering below Aquarius. This is Fomal- 
haut, of the first magnitude, the chief luminary 
of the southern constellation Pisces Austrcdis, 
the Southern Fish. This star is only seen on 
evenings when the horizon is specially clear. 

Pisces the Fishes the twelfth constella- 
tion of the Zodiac, is, like Aquarius, an unin- 
teresting constellation with no bright stars, but 
it is easy to follow, owing to the symmetrical 
arrangement of its stars. The chief stars be- 
ginning at the borders of Aquarius are Beta, 
Gamma, Iota, Omega, 41 Piscium, Epsilon, 
Mu, Nu, Xi, and Alpha. Another stream runs 
upwards from Alpha, and includes Pi, Eta, 
Rho, Chi, and Upsilon, Eta, and Gamma, the 
brightest stars of the constellation, are of the 
fourth magnitude. 

Cetus. To the left of Aquarius and lower 
down in the heavens than Pisces is the large 
constellation Cetus, the Whale. The figure of 
Cetus is fairly easy to follow. Mr. Maunder 
compares it to that of a lounge chair. Alpha, 
Gamma, Delta, and Omicron mark the head- 
rest of the chair. Zeta and Tau, Theta, Eta, 
and Beta form the lower portion of the figure. 
Alpha and Beta are of the second magnitude, 
Gamma, Zeta, Tau, Theta, and Eta of the 
third, and Delta of the fourth. The most re- 
markable star in the constellation is Omicron, 



THE STAES OF AUTUMN. 91 

generally known as " Mira Ceti " the won- 
derful star of Cetus. It is one of the most re- 
markable of variable stars. Unlike Algol and 
the other variables which have been noted in 
previous chapters, Mira runs through its cycle 
of variations not in days, but in months. The 
period is not regular, like the short-period vari- 
able stars, but varies considerably. On the 
average it is about 331 days. The star has 
been under observation for three centuries, and 
has been followed through many cycles. It 
varies from the third to the ninth magnitude 
as a rule, but sometimes at maximum it is 
much more brilliant, and has been known to 
reach the first magnitude. The variations of 
Mira have never received any completely satis- 
factory explanation ; they are certainly not 
due to eclipse, like Algol and Beta Lyrae. 
Probably they result from great internal 
disturbances. 

Eridanus and Aries. Between Cetus and 
Orion is Eridanus, the River, described in the 
chapter on the winter constellations. Above 
Cetus and to the left of Pisces and the right 
of Taurus is Aries, the Ram, the first of the 
zodiacal constellations. There are only three 
bright stars, Alpha, Beta, and Gamma, arranged 
in a neat little group, Beta and Gamma being 
close together. Alpha is of the second magni- 
tude, Beta of the third, and Gamma of the 



92 PKACTICAL ASTRONOMY. 

fourth. Gamma is a double star, the first 
discovered telescopically, in 1667 ; but it is 
beyond the reach of the binocular. 

Pegasus. Returning to Aquarius we recog- 
nise above that star-group a very noticeable 
constellation in a somewhat barren part of the 
sky Pegasus, or the Winged Horse. The 
most notable feature about Pegasus is the so- 
called " Great Square of Pegasus," although 
strictly speaking the title is incorrect, for the 



Fig. 11. Pegasus. 

star at the top left-hand corner belongs to the 
neighbouring constellation Andromeda. It is 
impossible to fail to recognise Pegasus. The 
great square is one of the most notable con- 
figurations in the heavens, not only on account 
of the brightness of the stars forming it, but 
also because of the dearth of bright stars 
within the figure itself. All four stars of the 
square are of the second magnitude. Beta 
Pegasi is at the top right-hand corner, Alpha 



THE STARS OF AUTUMN. 93 

at the bottom right-hand corner, and Gamma 
at the bottom left-hand corner. 

Close to Beta are Mu, and Lambda, of the 
fourth magnitude. An irregular quadrilateral 
is formed by Alpha, Zeta, Theta, and Epsilon, 
all of which are easily identified. 

Andromeda. Although Pegasus is so notice- 
able a constellation, it is singularly barren 
in interesting stars or binocular fields. Of 
more interest is the neighbouring constella- 
tion Andromeda. As already mentioned, Alpha 
Andromedae is the star at the top left-hand 
corner of the great square. 

Almost but not quite in a straight line with 
Alpha are Beta and Gamma Andromedae ; 
all three are of the second magnitude. Be- 
tween Alpha and Beta, but below the imaginary 
line joining them, are Delta of the third mag- 
nitude, and Epsilon of the fourth. Delta of 
the third and Epsilon of the fourth are almost 
in a straight line with Pi ; perpendicular to 
the line joining Alpha, Beta, and Gamma, is 
a line which almost joins Mu, Nu, and Beta. 
The star Nu is only interesting on account of 
its proximity to one of the most famous objects 
in the heavens the great nebula in Androm- 
eda. This famous nebula is easily visible to a 
person of average eyesight, being faintly visible 
to the unaided eye. It is well seen in a binoc- 
ular, and even in a small telescope it is a very 



94 PRACTICAL ASTRONOMY. 

impressive spectacle. This nebula rivals the 
great nebula in Orion as a celestial spectacle ; 
it has been closely studied by astronomers for 
many years, and since the application of 
photography to the heavens its study has 
proceeded with greater rapidity than ever. 
Formerly it was believed that the nebula was 
a cluster of stars, too distant for the individual 
stars to be separately visible. Later, the 
general view was that it was a true nebula, a 
mass of gas in a more condensed state than 
that in Orion. Recently, however, photo- 
graphic and spectroscopic research seems to 
indicate that it lies beyond the Stellar System 
and may possibly be an external galaxy, too 
far away for the individual stars to be sepa- 
rately visible. But in this case there is not the 
same degree of certainty as in that of the 
cluster in Hercules. 

In 1885 a temporary star appeared in the 
centre of the nebula. Other three have been 
detected in recent years. 

Between Andromeda and Aries is the little 
constellation of Triangulum, the Triangle. 
The constellation, like Delphinus and Sagitta, 
contains no stars of importance. Beta Trian- 
guli is of the third magnitude, and Alpha of 
the fourth. 

Next to Andromeda, Triangulum, and Aries, 
and to the left of these groups we come to the 



THE SOUTHERN STARS. 95 

constellations of Perseus and Taurus, discussed 
in the chapter on the .winter constellations. 
These fine groups come into prominence in 
the autumn, but it is in winter that they reach 
their most favourable position for observation. 



CHAPTER VII. 

THE SOUTHERN STARS. 

A distinguished writer on astronomy has 
remarked that " there is a strange unforget- 
table sensation in the first voyage from our 
high northern latitudes to the southern hemi- 
sphere. Besides the disappearance of old 
friends and the coming into sight of stranger 
stars, the known stars that still remain to us 
adopt most unfamiliar attitudes, and these 
become more and more perplexing the further 
south we go." In other words, a considerable 
number of the constellations visible in these 
latitudes are invisible in Australia, South 
Africa and South America, while the constella- 
tions which are visible here are seen inverted. 
As was seen in the preceding chapters, a 
considerable number of stars visible in the 
northern hemisphere do not set. On every 
clear night we are able to see the Plough, 
Cassiopeia, the Pole Star and other notable 



96 PKACTICAL ASTKONOMY. 

stars and constellations. A number of stars 
are visible to us in their different seasons, 
such as Orion, Leo, Virgo, and generally 
speaking, the constellations of the Zodiac ; 
while a considerable number of star-groups are 
totally invisible to us in the north, because 
they do not rise above our horizon. These 
are the southern circumpolar stars. Seen from 
the southern hemisphere, these stars do not 
set ; they occupy the same position to the 
inhabitants of the southern lands as the north- 
ern circumpolar stars do to us. To the dwellers 
in Australia, South Africa and South America, 
the Plough, Cassiopeia, and other northern 
star-groups are quite invisible ; on the other 
hand, Orion, Pegasus and the constellations of 
the Zodiac are visible from both hemispheres. 

The southern sky may be divided into two 
portions a portion rich in stars and a portion 
poor in stars. 

We may conveniently begin with Scorpio, a 
constellation which, as was noted in a previous 
chapter, is not seen to advantage in northern 
latitudes. In the south Scorpio is seen in its full 
magnificence high in the sky, almost exactly 
overhead. Following the course of the Galaxy 
here very brilliant we reach the constella- 
tions Lupus, or the Wolf, and Ara, the Altar. 
Lupus is a notable constellation, three of its 
stars being brighter than the third magnitude. 



THE SOUTHERN STARS. 97 

Following the course of the Galaxy we come 
to the three constellations, Centauries, or the 
Centaur ; Crux, or the Cross ; and Argo Navis, 
or the Ship Argo. These are three very famous 
groups. Centaurus has ten stars brighter than 
the third magnitude. Alpha and Beta, im- 
mersed in the stream of the Milky Way, are of 
the first magnitude, Alpha being indeed one 
of the most brilliant stars in the sky, inferior 
only to Sirius and Canopus in brilliance. 

< 



Fig. 12. Centaurus and Southern Cross. 

Alpha Centauri is interesting as the nearest 
of the stars. Its distance was measured in the 
years 1831-2 by Thomas Henderson, Astron- 
omer-Royal at the Cape of Good Hope, and 
afterwards Professor of Astronomy in the 
University of Edinburgh and Astronomer- 
Royal for Scotland ; and in point of fact it 
was the first star whose distance was success- 
fully measured. It is distant about twenty- 
five billions of miles from the Solar System. 
It is also well known as a binary, or revolving 

(2,015) 7 



98 PRACTICAL ASTRONOMY. 

double star. Recently Mr. R. T. A. Innes, of 
Johannesburg, has discovered a minute star at 
about the same distance and probably con- 
nected with the system of Alpha Centauri. 
It is the faintest known star in the Universe, 
its luminosity being only one ten-thousandth 
that of the Sun. 

Centaurus also contains other interesting 
objects, notably the magnificent cluster Omega 
Centauri. 

The Southern Cross is a small constellation 
in area, but it is a brilliant group, containing 
three stars brighter than the second magni- 
tude. It is thickly immersed in the stream of 
the Galaxy, and is perhaps rendered more 
noticeable by the wonderful gap in the Milky 
Way known as the " coal-sack." There is in 
the constellation Cygnus a rift in the Galaxy 
which has sometimes been named the " north- 
ern coal-sack," but the great gap in Crux has 
been described as truly an awe-inspiring object 
a region in the midst of " clusters and beds 
of worlds," yet destitute of stars. Here we 
seem to get a glimpse through the visible 
Universe itself into that region which has been 
designated the " darkness behind the stars." 

Leaving the Cross, the Galaxy passes into 
Argo Navis, a constellation so large that 
astronomers found it necessary many years 
ago to subdivide it into four smaller groups 



THE SOUTHEKN STARS. 99 

Malus, or the mast ; Vela, or the sails ; Puppis, 
or the stern, and Carina, or the keel. Argo 
contains fifteen stars brighter than the third 
magnitude, one of which is the well-known 
Canopus. This orb is, with the exception of 
Sirius, the brightest star in the sky, and its dis- 
tance is so vast that it can only be estimated. 

In this constellation too is situated Eta 
Argus, the famous " link " between variable 
and temporary stars. Originally an incon- 
spicuous star, it was observed by Sir John 
Herschel in 1838 to blaze up to the first mag- 
nitude, when it equalled Aldebaran in bril- 
liance. Five years later it equalled Canopus, 
and was one of the most brilliant stars in the 
sky. Since then the star has steadily de- 
creased in magnitude, and now it is barely 
visible to the unaided eye. 

After leaving Argo, the galactic stream 
passes into Canis Major, which is seen to 
greater advantage in the southern latitude 
than in the north ; this star-group, however, 
was described in an earlier chapter. 

We have described the course of the Galaxy 
in the southern hemisphere ; in other words, 
the rich region. The remaining portion of the 
southern circumpolar heavens is very poor in 
stars. The south celestial pole is situated in 
the constellation Octans a group very poor 
in stars, containing no orb as bright as the 



100 PRACTICAL ASTRONOMY. 

fourth magnitude. The star nearest the south- 
ern pole is Sigma Octanis, of the sixth magni- 
tude, just visible to the unaided eye ; so there 
is no south pole star in the true sense of the 
word. Round Octans are a number of star- 
groups equally inconspicuous Pavo, Mensa, 
Dorado, Hydrus, Toucan, Apus, &c. The 
paucity of bright stars is relieved by the 
presence of the two remarkable objects vari- 
ously known as the " Magellanic Clouds," 
" the Clouds of Magellan," and the " Nubec- 
ulae." These two objects are peculiar to the 
southern hemisphere, and have no counterpart 
in our northern skies. They are composed of 
stars, star-clusters and nebulae, and seem to 
form independent systems outside of the 
greater universe of stars. 

On the opposite side of the pole from the 
Cross is the constellation Eridanus, the north- 
ern part of which is to be seen in our latitudes. 
Its most brilliant parts, however, are only 
visible in the south. Its most brilliant star, 
Alpha, is also known by the Arabic name of 
" Achernar," " the end of the river." Finally, 
between Argo and Eridanus is Columba, the 
Dove, immediately south of Lepus, the little 
group below Orion. 

A number of these southern constellations 
such as Argo, Centaurus, Lupus, and Eridanus 
have been known from prehistoric times ; 



SUN, MOON, AND PLANETS. 101 

but the majority have only been known and 
named since European civilisation reached 
the southern hemisphere. Considering the 
advantages of later astronomers as compared 
with the circumstances of the early star- 
gazers who named our northern star-groups, 
it cannot be pretentied that they accomplished 
their work satisfactorily ; for the southern 
constellations, speaking generally, are not only 
difficult to identify, but are inappropriately 
named and grouped. 

The chief stars in the southern hemisphere 
are easily remembered, in the same way as 
those in the north the Cross and Achernar are 
at different sides of the Pole ; so are Argo and 
Scorpio. And with the march of the seasons 
their positions are constantly changing. 



CHAPTER VIII. 

SUN, MOON, AND PLANETS. 

We have now discussed the various constella- 
tions and the best method of recognising them 
and identifying their principal stars. These 
stars lie at immense distances from the Earth ; 
they form the background of the motions of 
the bodies of the Solar System. 

The ancient Greeks recognised seven bodies 



102 PRACTICAL ASTRONOMY. 

which were clearly not stars the Sun, the 
Moon, Mercury, Venus, Mars, Jupiter, and 
Saturn. All the stars which the ancients 
grouped into constellations were known to be 
fixed in position relatively one to the other. 
Sun, Moon, and planets were known to move 
round the starry sphere, and to have different 
motions. Indeed, the word " planet " is Greek 
for " wanderer." While the solar and lunar 
motions are regular, the planets obviously 
wander round tho heavens. 

The Zodiac. We may briefly consider the 
apparent motions of the Sun and Moon, and of 
the various planets, and also the best method 
of identifying the " wandering stars." The 
ancients recognised the fact that Sun, Moon, 
and planets moved round the heavens within 
a belt of sky which they termed the Zodiac, 
and which passed through the twelve con- 
stellations, Aries, Taurus, Gemini, Cancer, Leo, 
Virgo, Libra, Scorpio, Sagittarius, Capricornus, 
Aquarius, and Pisces. 

The Sun. The position of the Sun in the 
heavens is not so obvious as that of the Moon 
and planets ; but astronomers in prehistoric 
times were aware of the fact that the Sun 
moved round the sky in a path called the 
ecliptic, reaching right through the zodiacal 
constellations. In the chapters on the stars 
in their seasons we saw that some of the 



SUN, MOON, AND PLANETS. 10$ 

zodiacal constellations such as Taurus and 
Gemini are high in the heavens, and others 
such as Scorpio and Sagittarius are low down 
and not far above the horizon. Here, then,, 
we have the key to the seasonal changes. 
When the Sun in its apparent path is in the 
high constellations of the Zodiac it is summer ;. 
the orb of day is high above the horizon and is- 
visible for a protracted period ; when, on the 
other hand, the Sun is in Scorpio or Sagittarius 
it is winter. The Sun is low in the sky and is 
only visible for a comparatively short time. 
When the brilliant constellations of winter 
are on the meridian at midnight, the Sun is. 
in the zodiacal constellations opposite, namely, 
the " summer star-groups,'' Scorpio and Sagit- 
tarius. In summer the Sun is in the winter 
constellations. The reason of this tilting of the 
ecliptic is the fact mentioned in the first 
chapter, namely, that the axis of the Earth is 
not perpendicular to the plane of its orbit, but 
inclined twenty-three degrees. At the spring 
equinox, in March, day and night are equal 
all over the Earth at the poles and the 
equator. At this period both the poles are 
exposed to the Solar days in an equal degree ; 
but with the gradual revolution of the Earth 
in its orbit the northern hemisphere is inclined 
more and more to the solar beams, and the 
southern hemisphere less and less. Gradually 



104 PRACTICAL ASTRONOMY. 

spring passes into summer. At the summer 
solstice in June the days are much longer than 
the nights in the northern hemisphere, while 
in the southern the reverse state of things 
prevails. After June the period of daylight 
in the northern hemisphere gradually de- 
creases until in September day and night are 
equal all over the globe. The axis of the 
Earth is again upright relative to the Sun ; 
the northern hemisphere is tilted more and 
more away from the Sun as autumn passes 
into winter, until at the winter solstice it 
reaches its greatest inclination away from the 
sun the reverse state of affairs being the case 
in the south. After the winter solstice the 
period of daylight gradually increases, as the 
Earth is tilted more and more towards the 
solar beams until the spring equinox in March, 
when day and night are equal all over the globe. 
The result of this cycle of change is that in 
spring and autumn the Sun rises due east and 
sets due west ; in summer it rises in the north- 
east and sets north-west, and is about eighteen 
hours above the horizon just as is the case 
with the high constellations of the Zodiac, 
Taurus and Gemini ; in winter it rises in the 
south-east and sets in the south-west, and is 
above the horizon for a comparatively short 
time, as in the case of the low constellations 
of the Zodiac, Scorpio and Sagittarius. 



SUN, MOON, AND PLANETS. 105 

The seasons, then, are due to the inclination 
of the Earth's axis. But another cause is also 
at work, though in a very modified degree. 
The Earth's orbit is not a perfect circle, but 
an ellipse ; therefore at one point of its orbit 
the Earth is closer to the Sun than at the other. 
In our northern winter the Earth is three 
millions of miles nearer than in summer. 
Here we have an apparent paradox that the 
time of closest approach to the Sun is the 
time of greatest cold. When we consider the 
question, the apparent paradox soon dis- 
appears. In the northern hemisphere the 
lesser distance of the Sun modifies the rigours 
of winter, and its greater distance mitigates 
the warmth of summer. In the southern 
hemisphere, on the other hand, the conditions 
are reversed. The period of greatest heat 
occurs when the Sun is at its least distance, 
and that of greatest cold when it is furthest 
away. Thus the climate in the northern 
hemisphere is rendered more equable than 
that in the southern. 

To the observer without a telescope the Sun 
can scarcely be described as an interesting 
object. When spots are numerous, at the 
sun-spot maximum, the larger ones are some- 
times visible to the unaided eye through 
smoked glass. But the visibility of sun-spots 
to the unaided eye is a very rare occurrence. 



106 PRACTICAL ASTRONOMY. 

With a small telescope provided with a dark 
eyepiece many interesting observations on 
spots isolated and in groups may be made. 
To the observer provided with such an in- 
strument the Sun is a fascinating study. 

The Moon. The motion of the Sun round 
the heavens is only apparent. It is the Earth 
which moves along the ecliptic and causes the 
apparent motion of the orb of day. With the 
Moon the case is different. Alone of all the 
celestial bodies the Moon really revolves round 
the Earth. Its circuit of the zodiacal con- 
stellations represents a true motion. This 
circuit occupies 29 days and over 12 hours, 
roughly a month. In reality the Moon's 
period of revolution round the Earth is 27 days 
7 hours. The difference between the real and 
apparent periods is due to the Earth's revolution 
round the Sun. carrying the Moon along with it. 

The phases of the Moon have been noted 
from the earliest ages ; they are due to the 
fact that the Moon is a dark body shining by 
reflected light. At " new Moon " the Earth, 
the Moon, and the Sun are in a straight line, 
with the Moon in the middle position. The 
Sun is shining direct on the side of the Moon 
which is turned away from the Earth, and our 
satellite is invisible. At " first quarter " we 
only see half of the Moon illuminated. It is 
then at the point of its orbit, midway between 



SUN, MOON, AND PLANETS. 107 

"new Moon" and "full Moon." At full 
Moon the Sun, the Earth, and the Moon are in 
a straight line, with the Earth in the middle 
position. The Sun is shining directly on the 
Moon, and we see it fully illuminated, while 
at " last quarter " only half of the Moon is 
illuminated, as seen from Earth. 

Owing to its eastward motion along the 
Zodiac, the Moon rises about 50 minutes later 
each day. This is the average amount of 
delay, but the amount varies ; sometimes it 
is less than half an hour, sometimes an hour 
and a quarter. The difference depends on the 
angle which the Moon's path makes with the 
horizon ; this angle is least in the constellation 
Pisces, visible in autumn. Hence we have the 
phenomenon of the " Harvest Moon," when 
our satellite rises less than half an hour later 
every evening. 

There is much less moonlight in summer 
than in winter. At first this may seem to be 
due to the lengthened period of daylight 
the moonlight not being required and con- 
sequently not noticed ; such, however, is not 
the case. There is really less moonlight in 
summer than winter. This arises from the 
fact that before the Moon can be " full " and 
shining with complete radiance, it must be 
*' in opposition " to the Sun ; that is, situated 
in the diametrically opposite region of the sky. 



108 PRACTICAL ASTRONOMY. 

In winter the Sun is passing through the lower 
zodiacal constellations, consequently the Moon 
at the full phase passes through the higher. 
The full Moon at midwinter is in the same 
situation as the Sun at midsummer. Thus in 
winter there is more moonlight than sunlight. 
In summer the conditions are reversed. The 
Sun is in the higher constellations ; conse- 
quently the full Moon at midsummer occupies 
the place of the Sun at midwinter, and thus 
there is more sunlight than moonlight. 

The Moon may be studied by means of the 
binocular, and even in a small telescope it is 
a wonderful spectacle. 

The full phase of the Moon is the most useful 
to mankind, but it is not the most interesting 
to the astronomer. At that phase the Sun is 
shining direct on the Moon, and consequently 
the objects of the lunar surface cast no shadows. 
A view of the full Moon in a telescope is dis- 
tinctly disappointing. A few days before the 
full phase useful observations may be made. 
The astronomer, however, studies the Moon at 
all its phases ; in fact, it is only by long- 
continued observation that anything can be 
learned concerning our satellite. 

When one looks at the Moon through a 
telescope large or small for the first time, 
the most striking feature is the rugged and 
mountainous character of the lunar surface. 



SUN, MOON, AND PLANETS. 109 

The surface is diversified by great grey plains, 
which were once supposed to be seas, and 
mountainous uplands, comprising ranges of 
hills and mountains, and great numbers of 
walled plains and volcanic craters. These 
volcanic craters are by far the most numerous 
objects on the Moon. Volcanic action seems 
to have been much stronger on our satellite 
than our Earth relatively to size. However, 
this action seems to be now practically extinct, 
and the Moon is generally believed to be a dead 
world. Professor Pickering's studies indicate 
the possibility that a very thin atmosphere 
does exist, and that there is a rudimentary 
vegetation. But, even if this be so, we are 
correct in regarding the Moon as dead. 

The Planets. There can be little difficulty 
in identifying the principal planets Venus, 
Mercury, Mars, Jupiter, and Saturn. Of the 
seven chief planets of the Solar System outside 
of our own world, only these five are visible 
to the unaided eye. Uranus is practically 
invisible without the aid of a telescope, and 
Neptune absolutely so. 

Absolutely the larger planets are divided 
into two groups according to size the Inner 
Planets, comparatively close to the Sun, Mer- 
cury, Venus, the Earth, and Mars, compara- 
tively small in size ; and the Outer Planets 
beyond the ring of minor planets Jupiter, 



110 PRACTICAL ASTRONOMY. 

Saturn, Uranus, and Neptune, planets of large 
size. At present, however, we are discussing 
the heavens as they appear to us ; we are 
inhabitants of one of these inner planets, the 
Earth. Consequently the planets appear to 
us to be divided into two groups those which 
revolve round the Sun in orbits within the 
Earth's pathway, and those revolving without. 
These two groups are generally spoken of as 
the " inferior " and " superior " planets. In 
reality the more correct names are, the interior 
and exterior planets. The interior planets are 
Mercury and Venus, and the exterior planets 
Mars, Jupiter, and Saturn Uranus and Neptune 
being beyond the reach of the unaided vision. 
The two groups of planets have many points 
of difference. The interior planets, Venus and 
Mercury, are never seen far from the Sun. 
They can never be in " opposition " ; that is 
to say, they never rise at sunset, reach the 
meridian at midnight and set at sunrise. 
Neither is ever seen on an absolutely dark 
sky ; they seem to oscillate to and fro on 
either side of the orb of day. The exterior 
planets on the other hand are to be seen in all 
parts of the heavens ; they may be in " con- 
junction," invisible in the solar beams, or in 
" opposition," on the meridian at midnight 
and visible all night. Thus there are many 
more opportunities for observing the exterior 



SUN, MOON, AND PLANETS. Ill 

planets and their motions among the stars. 
These motions are much less simple than those 
of the Sun and Moon. The motion of the Sun 
along the ecliptic is simply the Earth's motion 
reflected in the heavens ; the Moon's circuit 
of the Zodiac is simply the actual revolution 
of the Moon round our world. But the 
planetary motions are a combination of real 
and apparent movements. The Earth is a 
planet, and in motion round the Sun ; the 
planets are also moving round the Sun. Hence 
the Earth's motion is partly reflected in the 
irregularities of the planetary motions. Thus 
the planets are sometimes apparently moving 
from west to east ; sometimes from east to 
west. Sometimes they appear almost sta- 
tionary. It is, however, no part of our present 
purpose to enter into a discussion of the 
planetary motions and their irregularities, 
which have attracted the attention of astron- 
omers and mathematicians in all ages. 

Venus is the most brilliant planet " the 
evening star " and " the morning star," the 
".Hesperus" and "Phosphorus" of the 
Greeks. From very early times the identity 
of the morning star and the evening star has 
been recognised. The late Professor Schia- 
parelli suggests that it was recognised so long 
ago as the epoch of the Book of Job ; he be- 
lieves " Mazzaroth in its season " to refer to 



112 PKACTICAL ASTKONOMY. 

the periodical appearances of Venus. Be this 
as it may, the motions of Venus have been 
familiar to mankind from the earliest ages. 

Venus is said to be at superior conjunction 
when the Earth, the Sun, and Venus are in 
a straight line, with the Sun in the middle. 
Venus, owing to its position within the Earth's 
orbit, exhibits phases similar to the Moon, and 
at this time it is fully illuminated, but is lost 
in the rays of the Sun. Then the planet 
emerges from the sunlight as " evening star." 
When it reaches the position known as " great- 
est elongation east " of the Sun, the disc seen 
through a small telescope is fully illuminated 
like the Moon at the quarters. As Venus 
draws nearer to the Earth the disc increases 
in size, but the illuminated portion decreases 
until the planet now a dwindling crescent 
is again lost in the rays of the Sun at the posi- 
tion known as " inferior conjunction." This 
position is analogous to "new Moon." The 
planet is invisible, as its dark side is turned 
towards the Earth. Shortly after this it 
reappears as a " morning star " ; it is at first 
a thin crescent, increasing in size until it 
reaches the position known as " greatest 
elongation west." It is now at its best posi- 
tion for observation as a morning star. Seen 
through the telescope the disc becomes smaller 
and more fully illuminated, until it again 



SUN, MOON, AND PLANETS. 113- 

reaches " superior conjunction," and is lost in 
the solar rays. The interval from conjunc- 
tion to conjunction superior conjunction to 
superior conjunction, or inferior to inferior 
is 584 days, and is known as the " synodic 
period " of Venus. 

Venus at times is exceptionally brilliant, and 
the ignorant have from time to time regarded 
the planet as a return of the " star of Beth- 
lehem," or as a portent. The phases of the 
planet are not visible to the unaided eye, but 
may be seen in a small telescope. These phases 
were discovered by Galileo three centuries ago 
with the newly-invented telescope. As a tele- 
scopic spectacle Venus is one of the most ex- 
quisite in the heavens, but owing to its thick 
atmosphere and the difficulty of observing it, 
little is known of its physical constitution. 

Mercury' passes through the same series of 
changes as Venus in a shorter time, its synodic 
period being 116 days. Like Venus, Mercury 
exhibits " phases," but these are not visible 
in the smallest telescopes. Mercury is very 
difficult of observation, and it is no small 
tribute to the skill and perseverance of the 
prehistoric astronomers that Mercury was 
known in those early times. The planet is 
never far from the Sun, and can only be seen 
at its elongations as morning or evening star. 
Even at these periods it is difficult to observe,. 

(2,015) 8 



114 PRACTICAL ASTRONOMY. 

and is only to be seen when the horizon is 
absolutely clear and free from clouds. It is 
recorded that Copernicus never succeeded in 
seeing the planet, although he often tried ; 
the explanation of his failure being that he 
lived on the banks of the Vistula, where the 
horizon is never free from the mists which 
rise from the river. 

The exterior planets Mars, Jupiter, and 
Saturn are to be seen in all parts of the 
Zodiac. None of them are so bright as Venus, 
but all are very noticeable. It is impossible 
to mistake or confuse them. Jupiter, gener- 
ally the superior of Mars, shines with a clear 
steady yellow light ; at times, however, Mars 
at its near approaches to the Earth is equal 
to Jupiter in brilliance. It shines with a 
steady fiery red light, from which peculiarity 
it was termed " the planet of war " by the 
ancients. Saturn, fainter than Mars or Jupiter, 
is equal in brilliancy to a star of the first 
magnitude ; it shines steadily with a dull 
yellow light. All three planets are to be seen 
in " opposition " to the sun when they rise 
at sunset and set at sunrise ; and as they 
make their nearest approaches at opposition, 
they have been closely studied both in tele- 
scopic and pre- telescopic times. 

The synodic period of Jupiter from con- 
junction to conjunction or opposition to oppo- 



SUN, MOON, AND PLANETS. 115 

sition is 399 days, and of Saturn 378 days. 
Thus the farther off a planet is, the shorter is 
its synodic period. With Mars the case is 
different ; the synodic period is 780 days, over 
two years. Mars is much closer to the Earth 
than Jupiter and Saturn, and its apparent 
motion is more complex. Oppositions of Mars, 
too, vary greatly in brilliance. The orbit of 
Mars is very elliptical in comparison with other 
planetary orbits. The pathways of Mars and 
the Earth approach nearest at the point occu- 
pied by the Earth about the end of August, 
and they diverge most at the point occupied 
by our world in February. Hence when Mars 
is in opposition in autumn it is very bright, 
and in spring much fainter. This, however, is 
somewhat modified by the fact that in spring 
the planet is in the high zodiacal constellations, 
and in autumn in the low star-groups. Favour- 
able oppositions, and also unfavourable, recur 
at intervals of about fifteen years. Thus there 
were very favourable oppositions, when the 
planet was very brilliant, in 1877, 1892, and 
1907, and unfavourable appearances in 1886, 
1901, and 1916. 

A small telescope will show the satellites of 
Jupiter and the ring of Saturn. It has been 
alleged that the satellites of the former planet 
have been seen with the unaided eye, but the 
evidence is far from conclusive. In a small 



116 PRACTICAL ASTRONOMY. 

telescope, however, they are easily seen, and 
form a beautiful telescopic spectacle. A small 
instrument will, however, show no features 
on Mars ; a good telescope is required to 
show the surface-markings, while the famous 
" canals " are only to be seen with powerful 
instruments in favourable climates. 



CHAPTER IX. 

ASTRONOMICAL PHENOMENA. 

Under the head of astronomical phenomena 
we include occurrences and appearances in the 
heavens eclipses of the Sun and Moon, tran- 
sits of Venus and Mercury, comets, meteors, 
the zodiacal light, and the Aurora Borealis. 
Such appearances attract a large amount of 
attention more, perhaps, than is their due. 

Eclipses and Transits. These kindred phe- 
nomena are due to the fact that every body 
in the universe shining by reflected light casts 
a shadow into space in a direction opposite to 
the source of illumination. Thus the Earth 
casts a shadow, and similarly Venus, Mars, 
Jupiter, and the other planets cast shadows. 
The shadows cast by the Earth and the Moon 
are the cause of the phenomena known as 
solar and lunar eclipses. The Earth casts a 




ASTKONOMICAL PHENOMENA. 117 

shadow, and when the Moon, the Earth, and 
the Sun are in a line, with our world in the 
middle, the terrestrial shadow which extends 
beyond the orbit of the Moon falls in the 
direction of our satellite. If the pathway of 
the Moon were exactly in the same plane or 
level as that of our world, it would pass through 
the shadow every time it reached the position 
known as full Moon. 

As a matter of fact, however, the Moon's 
orbit is not exactly in the same plane as that 
of the Earth, and only occasionally an eclipse 
does take place. Sometimes a lunar eclipse is 
total that is to say, the Moon is completely 
immersed in the Earth's shadow and some- 
times only partial, a portion of the disc re- 
maining outside the true shadow. A total 
eclipse of the Moon is a very remarkable and 
beautiful phenomenon. As the Moon becomes 
gradually immersed in shadow, the illuminated 
portion becomes smaller and smaller until it 
completely disappears. The Moon is not, how- 
ever, usually totally invisible. It generally 
assumes a dark copper-coloured hue, due to the 
refraction of sunlight through the atmosphere 
of the Earth. This is supposed to be due to 
the fact that the blue rays of the Sun are 
absorbed in traversing the atmosphere of the 
Earth, just as the sunset and sunrise skies 
assume a ruddy colour. 



118 PEACTICAL ASTRONOMY. 

Eclipses of the Sun take place at new Moon, 
when the Earth, the Moon, and the Sun are in 
a straight line, the Moon occupying the middle 
position. Sometimes the shadow of the Moon 
falls on our planet. This shadow is much 
smaller than the shadow of the Earth, and it 
only covers a small strip of territory on the 
globe ; to observers within this strip the Sun 
is for a few minutes totally eclipsed. Outside 
this strip there is a partial eclipse, part of the 
solar disc being obscured by the Moon. Occa- 
sionally an eclipse is partial without being total 
at any part of the Earth's surface. At times 
an eclipse is " annular," when the Moon is at 
the farthest point of its orbit and does not 
appear large enough to cover the Sun. At 
such times we are an " annulus " or ring of 
light round the Moon's disc. Of these three 
kinds of eclipses only total eclipses are useful 
to astronomers. This is owing to the fact that 
at such times the disc of the Moon appears 
large enough to cover the Sun, but not large 
enough, fortunately for astronomical science, 
to hide from view the immediate vicinity of 
the orb of day. 

Since the days of the early Chaldeans astron- 
omers have been familiar with a period by 
which the recurrence of solar and lunar eclipses 
can be predicted. This is known as the Saros. 
Its length is 18 years 111 days. In the words 



ASTRONOMICAL PHENOMENA. 119 

of an American astronomer, " At the end of 
this period the centres of the Sun and Moon 
return very nearly to their relative positions 
at the beginning of the cycle ; also certain 
technical conditions relating to the Moon's 
orbit and essential to the accuracy of the saros 
are fulfilled." Thus a total solar eclipse took 
place on May 17, 1882 ; it recurred on May 28, 
1900 ; and again on June 8, 1918. Eclipses, 
however, do not recur on the same part of 
the Earth's surface ; hence at any given place 
total solar eclipses are very rare. There has 
not been a total solar eclipse in the United 
Kingdom since 1724, and there will not be one 
visible until 1927. For those who have never 
seen a total eclipse, the following description 
by an American writer, Mrs. Todd, is worth 
reading, as illustrating the magnificence of the 
spectacle : " With frightful velocity the actual 
shadow of the Moon is often seen approaching, 
a tangible darkness advancing almost like a 
wall, swift as imagination, silent as doom. The 
immensity of Nature never comes quite so near 
as then, and strong must be the nerve not to 
quiver as this blue-black shadow rushes upon 
the spectator with incredible speed. Some- 
times the shadow engulfs the observers 
smoothly, sometimes apparently with jerks ; 
but all the world might well be dead and cold 
and turned to ashes. Often the very air seems 



120 PRACTICAL ASTRONOMY. 

to hold its breath for sympathy ; at other 
times a lull suddenly awakens into a strange 
wind, blowing with unnatural effect. Then out 
upon the darkness, gruesome but sublime, 
flashes the glory of the incomparable corona, 
a silvery, soft, unearthly light, with radiant 
streamers, stretching at times millions of un- 
comprehended miles into space, while the rosy 
flaming protuberances skirt the black rim of 
the Moon in ethereal splendour. It becomes 
ouriously cold, dew frequently falls, and the 
chill is frequently mental as well as physical. 
Suddenly, instantaneous as a lightning flash, 
an arrow of actual sunlight strikes the land- 
scape, and Earth comes to life again, while 
corona and protuberance melt into the return- 
ing brilliance." 

Transits are kindred phenomena to eclipses. 
Only the interior planets, Mercury and Venus, 
are to be seen in transit across the Sun. Tran- 
sits occur, like solar eclipses, when our world, 
Venus, and the Sun, or our world, Mercury, 
and the Sun are in a straight line. There is 
no eclipse, owing to the small apparent size of 
Mercury and Venus ; we merely see black discs 
as spots crossing the face of the Sun. 

Transits of Venus occur in pairs, separated 
by intervals of eight years ; and the pairs are 
separated by intervals of 105 J and 121 J years. 
There were transits in 1631 and 1639, 1761 



ASTRONOMICAL PHENOMENA. 121 

and 1769, 1874 and 1882; and the next pair 
will take place in 2004 and 2012. Transits of 
Mercury are much more frequent. 

Comets and Meteors. These kindred celes- 
tial bodies have attracted the attention of 
mankind from the earliest ages. Among the 
ancients and to the people of the Middle Ages 
comets were a source of terror, and were 
believed to be terrible portents of wars, fam- 
ines, and other national disasters. 

In the present day these feelings have given 
place to wonder and admiration. Of all celes- 
tial phenomena, comets attract the great- 
est and most widespread attention. In our 
present knowledge we may divide comets 
into two classes those which have been 
proved to revolve round the Sun and whose 
returns can be predicted, and those comets 
which have not been demonstrated to be 
members of the Sun's family. To the first 
class belongs the famous comet of Halley, 
whose last appearance in 1910 fell so far short 
of popular expectation ; and also the faint 
comet of Encke, which returns every three 
years, and others. Most of the periodic 
comets are faint, and do not attract atten- 
tion even when visible to the unaided eye. 

The brilliant comets of 1811, 1843, and 1858, 
and other notable comets of the last century, 
may or may not belong to the Solar System ; 



122 PRACTICAL ASTRONOMY. 

if they revolve round the Sun, they must do 
so in enormously long periods. Thus a bright 
comet appears, unexpectedly as a general 
rule ; its coming has not been predicted. This 
was the case with the only bright comet of 
recent years, the " great Daylight Comet " of 
January 1910. 

Meteors or shooting-stars are generally be- 
lieved to be the products of the dissolution 
of comets minute particles of matter which 
become ignited on entering the Earth's atmos- 
phere. They travel in ones, twos, threes, and 
in swarms or streams. The chief streams are 
the Leonids, Perseids, Lyrids, Andromedids, 
&c. ; but there are many others, and not a 
night passes without several meteors shooting 
across the sky. 

The study of meteors is one peculiarly 
adapted for the observer without a telescope ; 
indeed, in this branch of astronomy both 
telescope and binocular are useless. All our 
knowledge of meteors is due to observation of 
meteors time of flight, length of path, bril- 
liance, colour, &c. by the unaided eye ; and 
the greater part of the work in this branch of 
astronomy has been accomplished by one non- 
professional astronomer Mr. W. F. Denning 
of Bristol. 

A remarkable fact in connection with meteors 
is that from midnight to dawn is a much more 



ASTRONOMICAL PHENOMENA. 123 

favourable time for observation than from 
sunset to midnight. The explanation is that 
more meteors meet the Earth than overtake 
it, and as Mr. Maunder remarks " the Earth 
has its sunrise point in front as it moves for- 
ward in its orbit, its sunset point behind." 

The Zodiacal Light. This is a phenomenon 
which is much better seen in tropical than in 
temperate regions, but it is occasionally ob- 
served in Europe. A pearly glow is sometimes 
noticed in the spring to spread over a portion 
of the sky where the Sun has disappeared. In 
autumn the same phenomenon is also to be 
seen before sunrise. It is in tropical regions, 
however, that it is seen in its full glory. 
Instead of being seen like a cone, as in our 
latitudes, it appears as a band of light, and the 
portions near to the Sun seem as brilliant as 
the Galaxy. The exact nature of the zodiacal 
light has long been more or less of a mystery. 
The general idea among astronomers is that 
it is due to diffused dust, in all probability 
meteoric matter which forms an outer append- 
age to the Sun. Opposite in the heavens to 
the Light is a much fainter phenomenon known 
by its German name of " the Gegenschein," or 
counter-glow. Probably it is also of meteoric 
composition. 

The Aurora Borealis. This phenomenon, 
closely connected with the magnetism of the 



124 PRACTICAL ASTRONOMY. 

Earth, is one of the most striking of celes- 
tial spectacles. Properly speaking, the aurora 
should perhaps be classed among atmospheric 
phenomena, but its close connection with the 
sun-spot period renders it more directly akin 
to the heavens proper. 

The Aurora Borealis bhe "Northern Lights" 
is a regular phenomenon in the Arctic 
regions, and is often visible in the Shet- 
lands and Orkneys, the north of Scotland, 
and Northern Europe. In lower latitudes the 
aurora is a rare spectacle, and attracts 
a great deal of attention. It consists of 
streamers, bands, curtains, and rays of light 
of varying tints and different degrees of bril- 
liancy. These tremble and shoot up and down 
the sky with startling effect ; hence the popular 
name of the aurora " the Merry Dancers." 

In lower latitudes aurorae should be looked 
for more particularly when spots are numerous 
on the solar disc. Great storms in the Sun 
are generally accompanied by magnetic dis- 
turbances and brilliant auroral displays on the 
Earth. The nature of the connection has not 
been fully explained, but of its reality there is 
no doubt. 

In this chapter particular attention has been 
given to these astronomical phenomena which 
are of comparatively rare occurrence the 
appearance of bright comets, meteoric dis- 



ASTRONOMICAL PHENOMENA. 125 

plays, eclipses of the Sun and Moon. These 
phenomena never fail to awaken the curiosity 
and interest of the average man. It is well 
that they should ; and yet it is necessary to 
remember that wonderful as are eclipses, re- 
markable as are meteoric showers, far more 
wonderful, far more marvellous are the or- 
dinary facts which astronomy teaches us, far 
more awe-inspiring is a thoughtful glance into 
the immeasurable heavens. The marvellous 
power and energy of the Sun, the never-failing 
regularity of the Moon and planets in their 
eternal revolution, the vast distances and 
spaces, the calm shining of the changeless stars 
these are marvels visible to us daily and 
nightly, and we heed them not. Familiarity 
gives rise, if not to contempt, at least to in- 
difference. As Emerson has truly said : "If 
the stars should appear one night in a thousand 
years, how would men believe and adore, and 
preserve for many generations the remembrance 
of the City of God which had been shown." 



BIBLIOGRAPHY. 

The Constellations and How to Find Them. By 
William Peck, F.R.A.S. A series of monthly charts 
showing the chief stars and their position in the 
heavens. A useful guide for the beginner. (Gall & 
Inglis, Edinburgh.) 

Star-Groups. By J. Ellard Gore, F.R.A.S. A 
more advanced book than the last-named. There 
is a map for each constellation, and the individual 
stars are plainly marked. Probably the best book 
of its kind. (Crosby, Lockwood & Co., London.) 

Astronomy Without a Telescope. By E. Walter 
Maunder, F.R.A.S. A work descriptive of the 
heavens as seen with the unaided eye. The first part 
of the book describes the constellations season by 
season. The second and third parts describe ex- 
ercises and practical observations. An excellent 
work. (" Knowledge " Office, London.) 

A Popular Introduction to Astronomy. By Rev. 
A. C. Henderson. A little book by an amateur 
astronomer, who has worked out for himself the 
exercises in astronomy which he describes. (Manson, 
Lerwick, Shetland.) 

A New Astronomy. By Professor D. P. Todd. 
More advanced than the preceding books and less 
purely descriptive of the heavens, as they are. This 
work is most helpful to those beyond the stage of 
merely looking at and identifying the stars. (Samp- 
son, Low & Co., London.) 

Astronomy for Amateurs. By Camille Flammarion. 
This book is rather an astronomical survey than a 
guide to the heavens ; but it contains some chapters 
bearing on this branch of the subject. (Fisher 
Unwin, London.) 



INDEX. 



Alcor, 28. 

Alcyone, 46. 

Aldebaran, 7, 21, 44, 45, 53, 64, 

66, 99. 
Al Fard, 61. 
Algol, 50, 51, 91. 
Altair, 87. 

Anderson, T. D., 52. 
Andromeda, 37, 92, 93, 94. 
Antares, 77. 

Aquarius, 89, 90, 92, 102. 
Aquila, 79, 81, 86, 87, 88. 
Ara, 96. 

Arcturus, 66, 67, 68, 69. 
Argo Navis, 97, 98, 99, 100, 101. 
Aries, 19, 91, 102. 
Auriga, 33, 37, 47. 
Aurora Borealis, 116, 123. 

Ball, Sir R. S., 80. 
Barnard, E. E., 75. 
Bellatrix, 41. 
Betelgeux, 39, 40, 42, 43, 45, 54, 

64, 77. 
Bootes, 8, 64, 67, 69, 70, 75. 

Cancer, 61, 62, 102. 

Canes Venatici, 62. 

Canis Major, 21, 38. 

Canis Minor, 43. 

Canopus, 97, 99. 

Capella, 32, 33, 35, 48, 54, 64, 79. 

Capricornus, 88, 89, 102. 

Carlyle, T., 8. 

Cassiopeia, 29, 30, 31, 32, 33, 

34, 52, 95. 
Castor, 46, 47. 
Centauri, Alpha, 20, 75, 97. 
Centaurus, 20, 97, 98, 100. 
Cepheus, 34, 35. 
Ceres, 15. 
Cetus, 90, 91. 
Coma Berenices, 62. 
Comets. 15, 16, 121, 122. 
Copernicus, N., 114. 



Cor Caroli, 63. 

Corona Borealis, 64, 70. 

Corvus, 60. 

Crater, 60, 61. 

Cross, the Southern, 96, 98. 

Cygni (61), 84, 85. 

Cygnus, 8, 19, 81, 83, 85, 87, 98. 

Delphinus, 88, 94. 
Deneb, 84. 

Denning, W. E., 122. 
Draco, 8, 35. 
Dyson, Sir F. W., 22. 

Earth, 10, 11, 13, 14, 15, 20, 21, 
22, 23, 24, 57, 81, 82, 85, 86, 
101, 103, 104, 105, 109, 110, 
111, 112, 116, 117, 118, 124. 

Eclipses, 116, 117, 118, 119. 

Eddington, A. S., 22, 73. 

Elkin, W., 68, 69. 

Emerson, R. W., 125. 

Encke, J. F., 121. 

Eridanus, 47, 91, 100. 

Flammarion, C, 22, 38. 
Fomalhaut, 90. 

Galaxy, the, 22, 30, 60, 64, 65, 
78, 82, 83, 84, 85, 86, 87, 88, 
96, 98, 99, 123. 

Galileo, 113. 

Gemini, 44, 46, 48, 61, 102, 103, 
104. 

Goodrick, J., 51. 

Gore, J. E., 50, 65. 

Hale, G. E., 12. 

Halley, E., 121. 

Henderson, T., 97. 

Hercules, 71, 72, 73, 74, 75, 94. 

Herschel, Sir J., 99. 

Herschel, Sir W., 18, 35. 

Hesiod, 17, 25, 45. 

Homer, 17, 25, 42. 

Hyades, the, 44. 

Hydra, 61, 65. 



128 INDEX. 



Innes, R. T. A., 98. 

Job, 17, 25, 42, 45. 
Jupiter, 11, 15, 17, 18, 32, 102, 
109, 114, 115. 

Kapteyn, J. C, 22. 

Leo, 6, 55, 56, 57, 62, 63, 65, 96, 

102. 
Lepus, 38, 47, 100. 
Libra, 76, 102. 
Lowell, P., 14. 
Lupus, 96, 100. 
Lyra, 33, 79. 

Mars, 6, 11, 13, 14, 18, 77, 102, 

109, 114, 115, 116. 
Maunder, E. W., 5, 19, 30, 56, 

69 90 123. 
Mercury, 11, 13, 102, 109, 110, 

112, 113, 120. 
Meteors, 16, 57, 121, 122, 123. 
Milky Way. See Galaxy. 
Mirfak, 50. 
Mizar, 28._ 
Montanari, 51. 
Moon, the, 5, 10, 13, 16, 20, 23, 

101, 102, 106, 107, 108, 109, 111, 

116, 117, 118, 119, 120, 125. 

Neptune, 11, 15, 110. 
Newcomb, S., 80. 
Nova Persei, 87, 88. 

Ophiuchus, 71, 74. 
Orion, 7, 8, 18, 37, 38, 39, 41, 43, 
44, 45, 53, 54, 69, 77, 94, 96. 

Pegasus, 92, 93, 96. 
Perseus, 35, 37, 49, 50, 52, 95. 
Pickering, W. H., 14, 109. 
Pisces, 89, 90, 102. 
Pleiades, 18, 45, 62. 
Plough, the, 8, 25, 26, 27, 28, 

29, 30, 32, 33, 34, 35, 45, 55, 

63, 67, 95. 
Pole Star, the, 28, 30, 35, 95. 
Pollux, 46, 64. 
Praesepe, 62. 



Proctor, R. A., 85. 
Procyon, 42, 43, 64. 

Regulus, 56. 

Richter, J. P., 24. 

Rigel, 40, 41, 43, 47, 54, 64, 66. 

Sagitta, 87, 94. 

Sagittarius, 76, 78, 88, 102-104. 

Saros, 118. 

Saturn, 15, 102, 109, 114, 115. 

Schiaparelli, G. V., 14, 111. 

Scorpio, 38, 76, 77, 78, 88, 96, 

101, 102, 103, 104. 
Serpens, 71, 74, 75, 87. 
Serviss, G. P., 69. 
Shapley, H., 72, 73. 
Shelley, P. B., 23. 
Sirius, 7, 17, 19, 21, 43, 53, 64, 

66, 97. 
Solar System, the, 11, 16, 17, 

18, 19, 22, 23, 41, 42, 85, 101, 

121. 
Spica, 68, 64. 
Sun, the, 10, 12, 16, 21, 24, 40, 

41, 43, 56, 69 81, 85, 102, 103. 

104, 105, 106, 107, 108, 110, 111 

113, 116, 117, 123, 124, 125. 

Taurus, 21, 44, 48, 95, 102, 103, 

104. 
Tennyson, A., 44, 54. 
Todd, Mrs., 119. 
Triangulum, 94. 
Tycho Brahe, 32. 

Uranus, 11, 15, 110. 
Ursa Major, 25, 28. 
Ursa Minor, 29. 

Vega, 32, 33, 35, 66, 68, 79. 
Venus, 11, 13, 32, 102, 109, 110, 

111, 112, 113, 120. 
Virgo, 6, 58, 62, 63, 65, 96, 102. 
Vogel, H. C, 51. 

Wolf, M., 15. 

Zodiac, 96, 102, 103, 104, 107, 

111, 114. 
Zodiacal Light, the, 123. 



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