CONCLUDING CHAPTER

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 west382 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 constellation383 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.

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 find384 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.

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 you385 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.

Fig. 94.—Orion and Sirius.

Perseus lies in one of the richest parts of the heavens.387 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 with388 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,389 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 help390 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.