Mythology.

Queries.

Description.

A temporary

star.

Mythology.

Description.

Corvus was Coronis, a mortal princess, who was transformed into a crow by Minerva.

What is the color of ? Which star is the brightest of the group? How far from is the nearest visible star?

Corona Borealis.

The Northern Crown is a very satisfactory group, because the eye at once recognizes a similarity to the object which it is supposed to represent (Fig. 34). The constellation is just east

of the middle of the kite in Boötes. At the end of April it does not cross the meridian till 1 a. m. It is, at that time in the month, well up in the northeastern sky at 9 p. m. a, also called Alphecca or Gemma, is FIG. 34.-CORONA BOREALIS. 10° east of Boötis. 1° south of e is situated T Coronæ, one of the small number of temporary stars. In May, 1866, it blazed forth suddenly, equalling Alphecca in magnitude. After it was discovered it declined in brightness, and had sunk below the eighth magnitude by the end of the month. An opera-glass now shows it as a star of the ninth magnitude.

The crown belongs to Ariadne, whom Bacchus made his wife. He gave it to her at the time of the marriage, and afterward placed it among the stars.

Hydra.

Hydra is an immense snake, whose head is just south of the A in Cancer; the end of its tail is south of the

feet of Virgo. a, also called Cor Hydræ, is in its heart (Fig. 35). A line from Polaris running in front of the sickle in Leo (being 4° away from & Leonis, which is at the point of the sickle-blade), when prolonged to a point 25° distant from a Leonis, meets Cor Hydræ. From Cor the snake's body winds eastward and southward, passing immediately beneath Corvus, and stretching 30° eastward to a group of small stars, which lies 20° south of Virginis. A line from Corvi to & Corvi prolonged 13° meets .

Chinese astronomers are said to have particularly observed Cor Hydræ over 4,000 years ago. Their records

Cor Hydræ.

FIG. 35.-HYDRA.

show that in the reign of the emperor Tao it crossed the meridian at sunset, at the time of the vernal equinox. (March 20 in the modern calendar).

e is a fine double for a three-inch telescope; one component is yellow, the other blue.

Hercules was sent to kill a monster which was ravaging Mythology. the country of Lerna, near Argos, and which has been called the Lernean hydra. It had nine heads, one of which was immortal. Whenever Hercules struck off a mortal head with his club, two others grew out to take

Queries.

its place. He finally burned the mortal heads, and buried the immortal one under a rock. As is fitting, we find the immortal head in the sky, close by Cancer, the Crab, which assisted Hydra in the fight and succeeded in wounding Hercules.

What is the color of Cor Hydra? A line from € Corvi to Corvi, prolonged eastward 10°, strikes what star in Hydra? At the end of the tail of Hydra are two fifth magnitude stars 3° apart; how many faint stars can be seen between them?

CHAPTER VI.

THE CONSTELLATIONS FOR MAY AND JUNE.

"Awake, my soul,

And meditate the wonder! Countless suns

Blaze round thee, leading forth their countless worlds."

Lyra.

-Ware.

Vega

ONE who looks for this constellation early in May should observe it as late in the evening as is convenient. At 9 p. m. it is in the northeast, not very high up. It will probably be recognized at once because of the brilliancy of Vega, its leading star (Fig. 36). The parallelogram formed by ß, y, d, and will be below and at the right of Vega. The distance from Vega to is only 8°. Vega is nearly equidistant from Polaris and the star at the end of the tail of the Great Bear, being over 40° from each.

FIG. 36.-LYRA.

Vega is one of the most beautiful, as well as one of the brightest stars. It is 120 millions of millions of miles from us, and thirty times as bright as the sun. Light consumes twenty years in coming to us from it. It is approaching us at the rate of ten miles a second. It will be the pole-star 12,000 years hence.

e is one of the most famous of multiple stars.

An

Description.

Vega.

average eye perceives that it is oblong, and a good eye Epsilon Lyræ. splits it into two. With a three-inch telescope each of the stars is again divided into two components. Both pairs revolve, one in a period of 2,000 years, the other in 1,000 years.

A variable.

An elliptical nebula.

Mythology.

Queries.

Description.

ẞ is a variable star, which changes from magnitude 3.3 to 4.5, being alternately brighter and fainter than 7. Its period is nearly thirteen days. There are curious anomalies in its changes, for which astronomers have yet found no reasonable explanation.

The only elliptical nebula which a small telescope will show is one third of the way from to 7. In a large telescope it is an exceedingly beautiful object. Were the sun in the center of it, the planet Neptune would not lie outside of it.

Lyra is the golden harp given by Apollo to Orpheus : not only wild beasts were charmed by its sweet strains, but even trees and rocks, which moved from their places to follow the harper. With it Orpheus descended to Hades, stopped the sound of torment by its music, and won back his dead wife, melting stern Pluto's heart.

Is & double to the naked eye? What is the color of Vega? Is Vega above the horizon more or less than twelve consecutive hours?

Hercules.

A large part of Hercules lies between Lyra and Corona Borealis. It therefore appears to be above Lyra when seen low in the east. During May a better view of it can be obtained after 9 p. m. than before that hour. The giant is represented with his head toward the equator and his feet toward the north pole (Fig. 37). a is in the head; the shoulders are marked by ẞ and 8; e and are in the belt. The positions of the limbs