For a while Sirius was believed to be traveling in a straight line, but soon irregularities were discovered in the great star's motion, an "undulatory progressive motion" on each side of a middle line. From a knowledge of these oscillating movements, Bessel inferred that Sirius must have an unseen companion attracting or pulling it as the two stars traveled together around a common center of gravity. In 1862, Mr. Alvan G. Clarke of New York detected this companion situated at an angular distance of only 7" from Sirius,--about as far distant as Uranus is from the earth. The larger star is only about twice as massive as its companion but is 20,000 times brighter. The light that we see from Sirius then comes from two stars which together radiate 48 times as much light as the sun. Compared to Sirius, our sun is rather an inconspicuous star, although Barnard gave us great satisfaction by discovering a neighbor not much farther away than Sirius which gives out only ¹⁄₂₅₀₀ as much light as the sun! Sirius, the "Dog Star," rests on the nose of the Great Dog, in the constellation Canis Major, and may be found in a straight line from the three evenly spaced stars in Orion's Belt. He was originally Orion's hunting dog, and, as if to give atmosphere to a hunting scene in the sky, Lepus, the Hare, has been placed on a constellation just in front of Sirius and below the feet of Orion, where he is "pursued continually through all time" by the Dog with the huge star. A vividly red variable star glows in the constellation of Lepus, the Hare. Every so often, this little star becomes radiantly red. This additional light is caused by the star bursting explosively through the layer of absorbent vapors which are smothering the life from its flames. Some day this crimson star will flare and flicker for the last time and its final ray be wafted to our earth--the Swan Song of a dying star. About 9 o'clock during the first part of December, Sirius rises on its pathway south of east, the brilliant beauty of its light adding to the celestial scene like a torch among a thousand candles. This is true though the month of December exhibits the loveliest assembly of stars to be seen in all the year. From December on into early spring, the Dog Star is the cynosure of every eye. Night after night, through the winter evenings, it flashes in the sky a little farther west; finally it gleams in the western sky at sunset, jewels the rim of the horizon, and disappears. [Figure 106: Orion and the "Dog Star."] [Figure 107: THE WINTER BATTLE OF ORION, THE GIANT, AND TAURUS, THE BULL. These beautiful constellations first make their appearance during October, although they may be viewed to better advantage during the winter-time, when they lie directly in the south.] CHAPTER IX THE STORY OF ORION AND TAURUS, THE BULL ORION, THE MIGHTY HUNTER [Figure 108]