Every one who wishes to learn something about astronomy should
make a determined effort to become acquainted with the principal
constellations, and to find out the names of the brighter and more
interesting stars. I have therefore added to STAR-LAND this little
chapter, in which I have tried to make the study of the stars so simple
that, by taking advantage of a few clear nights, there ought to be no
difficulty in obtaining a knowledge of a few constellations.
The first step is to become familiar with the Great Bear, or Ursa
Major, as astronomers more generally call the group. We begin with
this, because after it has been once recognized, then you will find
it quite easy to make out the other constellations and stars. It may
save you some trouble if you can get some one to point out to you
the Great Bear; but even without such aid, I think you will be able
to make out the seven bright stars which form this remarkable group,
from the figure here given (Fig. 92). Of course, the position of this
constellation, as of every other in the heavens, changes with the hour
of the night, and changes with the seasons of the year. About April
the constellation at 11 o’clock at night is high over your head. In
September at the same hour, the Great Bear is low down in the north.
It is to be seen in the west in July, and at Christmas it lies in
the east at convenient hours in the evening for observation. One of
the advantages of using the Great Bear as the foundation of our study
of the stars arises from the fact that to an observer in the British
Islands or in similar latitudes this group never sets. Whenever the sky
is clear after nightfall, the Great Bear is to be seen somewhere, while
the brightness of its component stars makes it a conspicuous object.
Indeed, there is only one constellation in the sky, namely, that of
Orion, which is a more brilliant group than the Great Bear. We shall
tell you about Orion presently, but it does not suit to begin with,
because it can only be seen in winter, and is then placed very low down
in the heavens.
[Illustration: FIG. 92.--The Great Bear and the Pole Star.]
Your next lesson will be to utilize the Great Bear for the purpose of
pointing out the Pole Star. Look at the two stars marked α and β. They
are called the “Pointers,” because if you follow the direction they
indicate along the dotted line in the figure, they will conduct your
glance to the Pole. This is the most important star in the heavens to
astronomers, because it happens to mark very nearly the position of
the Pole on the sky. You will easily note the peculiarity of the Pole
Star if you will look at it two or three times in the course of the
night. It will appear to remain in the same place in the sky, while the
other stars change their places from hour to hour. It is very fortunate
that we have a star like this in the northern heavens; the astronomers
in Australia or New Zealand can see no bright star lying near the
Southern Pole which will answer the purposes that the Pole Star does so
conveniently for us in the north.
The Pole Star belongs to a constellation which we call the Little Bear;
two other conspicuous members of this group are the two “Guards”; you
will see how they are situated from Fig. 82, p. 322. They lie nearly
midway between the Pole Star and the last of the three stars which
form the Great Bear’s Tail. The same figure will also introduce us to
another beautiful constellation, namely, Cassiopeia. You will never
find any difficulty in identifying the figure that marks this group if
you will notice that the Pole lies midway between it and the Great Bear.
[Illustration: FIG. 93.--The Great Square of Pegasus.]
Cassiopeia is also one of the constellations that never set to British
observers; but now we have to speak of groups which do set, and which,
therefore, can only be observed when the proper season comes round. The
first of these is “the Great Square of Pegasus”; you cannot see this
group conveniently in the spring or summer, but during the autumn and
winter it is well placed after nightfall. There are four conspicuous
stars forming the corners of the square, and then three others marked
α, γ, and β (Fig. 93), which form a sort of handle to the square. In
fact, if you once recognize this group, you will perhaps see in it a
resemblance to a great saucepan with a somewhat bent handle, and then
you will be acquainted with a large tract of Star-land near the Square
of Pegasus. From the figure you will see that a line imagined to be
drawn from the Pole Star over the end of Cassiopeia, and then produced
as far again, will just lead to the Great Square. I have also marked on
this figure two objects that are of great telescopic interest; one of
them is the Nebula in Andromeda, of which we had an account in the last
lecture. You see it lies halfway between the corner α of the square and
the group of Cassiopeia. Another interesting object is the star marked
γ Andromedæ. The telescope shows it to consist of a pair of stars, the
colors of which are beautifully contrasted.
At the end of this handle to the Great Square of Pegasus is the star
α, in the constellation of Perseus. It lies between two other stars γ
and δ. We refer to Fig. 84, in which these stars are shown. We there
employed the figure to indicate the position of Algol, the remarkable
variable star. Your map will also point out some other important
stellar features. If we curve round the three marked γ, α, and δ of
Perseus, the eye is conducted to Capella, a gem of the first magnitude
in the constellation of Auriga. Close to Capella is a long triangle,
the corners of which are the “Hœdi,” the three kids--which Capella is
supposed to nurture.
If we carry a curve through γ, α, δ, of Perseus, and now bend it in the
opposite way, the eye is led through ε and ζ in the same constellation,
and then on to the Pleiades, of which we have already spoken.
[Illustration: FIG. 94.--Orion and Sirius.]
Perseus lies in one of the richest parts of the heavens. The Milky
Way stretches across the group, and the sky is strewn with stars beyond
number. Even an opera-glass directed to this teeming constellation
cannot fail to afford the observer a delightful glimpse of celestial
scenery.
We may, however, specially remind the beginner that the objects on
this map are not always to be seen, and as an illustration of the way
in which the situation and the visibility of the constellations are
affected by the time of year, I shall take the case of the Pleiades and
follow them through a season. Let us suppose that we make a search for
this group at 11 P.M. every night. On the 1st of January, the Pleiades
will be found high up in the sky in the southwest. On the 1st of March,
they will be setting in the west at the same hour. On the 1st of May,
the Pleiades are not visible, neither are they on the 1st of July. On
the 1st of September, they will be seen low down in the east. On the
1st of November, they will be high in the heavens in the southeast. On
the ensuing 1st of January, the Pleiades will be found back in the same
place which they occupied on the same date in the preceding year, and
so on throughout the cycle. Of course, you will not suppose that their
changes are due to actual motions in the group of stars themselves.
They are merely apparent, and are to be explained by the motion of the
earth round its axis, and the revolution around the sun.
Next we are to become acquainted with the glory of our winter skies,
the constellation of Orion, Fig. 94. I dare say many of my readers are
already familiar with the well-known twin stars which form the belt of
Orion, but if not, they will be able to recognize it by the help of the
groups already learned. Imagine a line drawn from the Pole Star through
Capella, and then produced as much further again, and we shall be
conducted into the precincts of Orion. This group lies on the equator,
and, consequently, it is equally familiar to southern astronomers and
to those of the north. It can be best seen by those who observe it from
or near the equator.
The brightest star in Orion is known either as α Orionis or as
Betelgeuze, by which name it is represented in the figure. This star
is of the first magnitude, and so is Rigel on the opposite side of the
belt. The three stars of the belt and the two others, γ and κ, at which
they point above and below, are of second magnitude.
The owner of a telescope finds especial attractions in this
constellation. Notably among the subjects which will interest him is
the Great Nebula, the position of which is indicated in our figure.
Under the middle of the belt are a few stars, around which is a hazy
light that is perceptible with the smallest telescopic aid. Viewed
by instruments of adequate proportions, these have developed into a
marvellous nebula of glowing gas, attaining to dimensions so vast that
no one has yet ever attempted to estimate them.
The vicinity of Orion is also enriched with some of the most
interesting stellar objects. Follow the line of the belt upwards to
the right, and your eye is conducted to a ruddy first magnitude star
named Aldebaran, in the constellation of the Bull. This is a pleasing
object, which the beginner will sometimes be apt to confuse with the
planet Mars, to which, under certain circumstances, it certainly bears
a resemblance. Another very pleasing little group, known as the Hyades,
will be found near Aldebaran. If the line of the belt of Orion be
carried down to the left, it will be found to point to Sirius, or the
Dog Star.
You will find it an interesting occupation to make for yourself maps
of small parts of the heavens. First copy out the chief stars in their
proper places from the star atlas, and then fill in the smaller stars
with your own observations. Try first on some limited region of the
heavens; take the figure of Cassiopeia, for instance, or the Square
of Pegasus, and see if you can produce a fair representation of those
groups by marking in the stars that your instrument will show you;
or take the Pleiades and make a tracing of the principal stars of
the group from the sketch that we have given (Fig. 89), then take an
opera-glass and fill in as carefully as you can all that it will show.
I can assure you that you will find a little definite work of this kind
full of interest and instruction.
But I hope you will desire to advance further in the study of the
heavens. It is to be remembered that with even the most moderate
instruments there is much to be done. Many comets have been detected,
and many planets have been discovered, by the use of telescopes so
small that they could be easily carried out from the house for the
evening’s work and brought back again after the observations were over.
It remains for me to add a few words which will help you in finding
the planets. It is, of course, impossible to represent such objects
as Jupiter, Saturn, Venus, Mars, and Mercury on maps of the heavens,
because these bodies are constantly moving about, and if their places
were right to-day they would be wrong to-morrow. The almanac will be
necessary for you here. You must find out by its help what planets are
visible and in what part of the sky they are placed. Then you will
have to compare your maps with the heavens, and when you find a bright
star-like body that is not shown on your maps you may conclude at once
that it is the planet. Although these objects are so star-like to the
unaided eye, yet the resemblance is at once dispelled when we use a
telescope. The star is only a bright point of light and white, the
planet shows a visible shape. This is, at least, the case with the five
planets I have named; for there are others, such as Uranus and Neptune,
which are too far to be much more than star-like points in ordinary
telescopes. The minor planets would not interest you.
I hope that the reading of STAR-LAND will, at all events, induce you to
make a beginning of the study of the heavens, if you have not already
done so. If you have the advantage of a telescope, so much the better;
but, if this is impossible, make the best use of your own eyes. Do not
put it off or wait till you get some one to teach you. If it be clear
this very night, go out and find the Great Bear and the Pole Star, and
as many of the other constellations as you can, and at once commence
your career as an astronomer.