Astronomy for Amateurs Part 3

The Scorpion, held to be a sign of ill luck, has been prejudicial to the Archer, which follows it, and traces an oblique trapezium in the sky, a little to the east of Antares. These two southernmost constellations never rise much above the horizon for France and England. In fable, the Archer is Chiron, the preceptor of Jason, Achilles and aesculapius.

Capricorn lies to the south of Altar, on the prolongation of a line from the Lyre to the Eagle. It is hardly noticeable save for the stars [alpha] and [beta] of third magnitude, which scintillate on its forehead.

The Water-Carrier pours his streams toward the horizon. He is not rich in stars, exhibiting only three of third magnitude that form a very flattened triangle.

Lastly the Fishes, concluding sign of the Zodiac, are found to the south of Andromeda and Pegasus. Save for [alpha], of third magnitude, this constellation consists of small stars that are hardly visible.

These twelve zodiacal constellations will be recognized on examining the chart (Figs. 10-11).

We must now visit the stars of the Southern Heavens, some of which are equally deserving of admiration.

[Ill.u.s.tration: FIG. 10.--The Constellations of the Zodiac: summer and autumn; Capricorn, Archer, Scorpion, Balance, Virgin, Lion.]

It should in the first place be noted that the signs of the Zodiac and the Southern Constellations are not, like those which are circ.u.mpolar, perpetually visible at all periods of the year. Their visibility depends on the time of year and the hour of the night.[4]

In order to admire the fine constellations of the North, as described above, we have only to open our windows on a clear summer's evening, or walk round the garden in the mysterious light of these inaccessible suns, while we look up at the immense fields in which each star is like the head of a celestial spear.

But the summer is over, autumn is upon us, and then, too soon, comes winter clothed in h.o.a.r-frost. The days are short and cold, dark and dreary; but as a compensation the night is much longer, and adorns herself with her most beautiful jewels, offering us the contemplation of her inexhaustible treasures.

[Ill.u.s.tration: FIG. 11.--The Constellations of the Zodiac: winter and spring; Crab, Twins, Bull, Ram, Fishes, Water-Carrier.]

First, let us do homage to the magnificent Orion, most splendid of all the constellations: he advances like a colossal giant, and confronts the Bull.

This constellation appears about midnight in November, in the south-eastern Heavens; toward eleven o'clock in December and January, due south; about ten in February, in the south-east; about nine in March, and about eight in April, in the west; and then sets below our horizon.

[Ill.u.s.tration: FIG. 12.--Orion and his celestial companions.]

It is indisputably the most striking figure in the sky, and with the Great Bear, the most ancient in history, the first that was noticed: both are referred to in the ancient texts of China, Chaldea, and Egypt.

Eight princ.i.p.al stars delineate its outline; two are of the first magnitude, five of the second, and one of the third (Fig. 12). The most brilliant are Betelgeuse ([alpha]) and Rigel ([beta]): the former marking the right shoulder of the Colossus as it faces us; the second the left foot. The star on the left shoulder is [gamma] or Bellatrix, of second magnitude; that of the right foot, [chi], is almost of the third.

Three stars of second magnitude placed obliquely at equal distances from each other, the first or highest of which marks the position of the equatorial line, indicate the Belt or Girdle. These stars, known as the Three Kings, and by country people as the Rake, a.s.sist greatly in the recognition of this fine constellation.

A little below the second star of the Belt, a large white patch, like a band of fog, the apparent dimensions of which are equal to that of the lunar disk, is visible to the unaided eye: this is the Nebula of Orion, one of the most magnificent in the entire Heavens. It was discovered in 1656 by Huyghens, who counted twelve stars in the pale cloud. Since that date it has been constantly studied and photographed by its many admirers, while the giant eye of the telescope discovers in it to-day an innumerable mult.i.tude of little stars which reveal the existence of an entire universe in this region.

Orion is not merely the most imposing of the celestial figures; it is also the richest in sidereal wonders. Among these, it exhibits the most complex of all the multiple systems known to us: that of the star [theta] situated in the celebrated nebula just mentioned. This marvelous star, viewed through a powerful telescope, breaks up into six suns, forming a most remarkable stellar group.

This region is altogether one of the most brilliant in the entire firmament. We must no longer postpone our homage to the brightest star in the sky, the magnificent Sirius, which shines on the left below Orion: it returns every year toward the end of November. This marvelous star, of dazzling brilliancy, is the first, [alpha], in the constellation of the Great Dog, which forms a quadrilateral, the base of which is adjacent to a triangle erected from the horizon.

When astronomers first endeavored to determine the distance of the stars, Sirius, which attracted all eyes to its burning fires, was the particular object of attention. After long observation, they succeeded in determining its distance as 92 trillion kilometers (57 trillion miles). Light, that radiates through s.p.a.ce at a velocity of 300,000 kilometers (186,000 miles) per second, takes no less than ten years to reach us from this sun, which, nevertheless, is one of our neighbors.

The Little Dog, in which Procyon ([alpha], of first magnitude) shines out, is above its big brother. With the exception of [alpha], it has no bright stars.

[Ill.u.s.tration: FIG. 13.--Winter Constellations.]

Lastly, toward the southern horizon, we must notice the Hydra, Erida.n.u.s, the Whale, the Southern Fish, the Ship, and the Centaur. This last constellation, while invisible to our lat.i.tudes, contains the star that is nearest to the Earth, [alpha], of first magnitude, the distance of which is 40 trillion kilometers (25 trillion miles).

[Ill.u.s.tration: FIG. 14.--Spring Constellations.]

The feet of the Centaur touch the Southern Cross, which is always invisible to us, and a little farther down the Southern Pole reigns over the icy desert of the antarctic regions.

[Ill.u.s.tration: FIG. 15.--Summer Constellations.]

[Ill.u.s.tration: FIG. 16.--Autumn Constellations.]

In order to complete the preceding descriptions, we subjoin four charts representing the aspect of the starry heavens during the evenings of winter, spring, summer, and autumn. To make use of these, we must suppose them to be placed above our heads, the center marking the zenith, and the sky descending all round to the horizon. The horizon, therefore, bounds these panoramas. Turning the chart in any direction, and looking at it from north, south, east, or west, we find all the princ.i.p.al stars. The first map (Fig. 13) represents the sky in winter (January) at 8 P.M.; the second, in spring (April) at 9 P.M.; the third, in summer (July) at the same hour; the fourth, the sky in autumn (October) at the same time.

And so, at little cost, we have made one of the grandest and most beautiful journeys conceivable. We now have a new country, or, better, have learned to see and know our own country, for since the Earth is a planet we must all be citizens of the Heavens before we can belong to such or such a nation of our lilliputian world.

We must now study this sublime spectacle of the Heavens in detail.

CHAPTER III

THE STARS, SUNS OF THE INFINITE

A JOURNEY THROUGH s.p.a.cE

We have seen from the foregoing summary of the princ.i.p.al Constellations that there is great diversity in the brightness of the stars, and that while our eyes are dazzled with the brilliancy of certain orbs, others, on the contrary, sparkle modestly in the azure depths of the night, and are hardly perceptible to the eye that seeks to plumb the abysses of Immensity.

We have appended the word "magnitude" to the names of certain stars, and the reader might imagine this to bear some relation to the volume of the orb. But this is not the case.

To facilitate the observation of stars of varying brilliancy, they have been cla.s.sified in order of magnitude, according to their apparent brightness, and since the dimensions of these distant suns are almost wholly unknown to us, the most luminous stars were naturally denoted as of first magnitude, those which were a little less bright of the second, and so on. But in reality this word "magnitude" is quite erroneous, for it bears no relation to the ma.s.s of the stars, divided thus at an epoch when it was supposed that the most brilliant must be the largest. It simply indicates the apparent brightness of a star, the real brilliancy depending on its dimensions, its intrinsic light, and its distance from our planet.

And now to make some comparison between the different orders. Throughout the entire firmament, only nineteen stars of first magnitude are discoverable. And, strictly speaking, the last of this series might just as well be noted of "second magnitude," while the first of the second series might be added to the list of stars of the "first order." But in order to form cla.s.ses distinct from one another, some limit has to be adopted, and it was determined that the first series should include only the following stars, the most luminous in the Heavens, which are subjoined in order of decreasing brilliancy.

STARS OF THE FIRST MAGNITUDE

1. Sirius, or [alpha] of the Great Dog.

2. Canopus, or [alpha] of the Ship.

3. Capella, or [alpha] of the Charioteer.

4. Arcturus, or [alpha] of the Herdsman.

5. Vega, or [alpha] of the Lyre.

6. Proxima, or [alpha] of the Centaur.

7. Rigel, or [beta] of Orion.

8. Achernar, or [alpha] of Erida.n.u.s.

9. Procyon, or [alpha] of the Little Dog.

10. [beta] of the Centaur.

11. Betelgeuse, or [alpha] of Orion.

12. Altar, or [alpha] of the Eagle.

13. [alpha] of the Southern Cross.

14. Aldebaran, or [alpha] of the Bull.

15. Spica, or [alpha] of the Virgin.

16. Antares, or [alpha] of the Scorpion.

17. Pollux, or [beta] of the Twins.

18. Regulus, or [alpha] of the Lion.