Sirius
in astronomy, the dog log star, by far the brightest fixed star in the sky.
It is alpha Canis Major, situated a little below Orion, and is mythologically regarded as one of the hounds held in leash the other. A line drawn from the Plei-. the other. A ades through the three stars of Orion's belt will pass it closely; straight lines connecting it with Procyon and Betelgeuse will constitute a nearly equilateral triangle; and Aldebaran, Betelgeuse, Sirius, and Regel, all of the first magnitude, form a lozenge-shaped figure, with Orion's belt in the center. Ptolemy, in the 2d century, ranked Sirius among red stars; now it is white, and is a very brilliant object, its light being 324 times as great as that of a star of the sixth magnitude.
It is about 1,000,000 times as far from us as the sun, and its mass is about 20 times as great. Viewed by the spectroscope, its chief lines are those of incandescent hydrogen, with feebler ones of sodium and magnesium; the metal mercury seems also to be present. Some irregular movements of Sirius led to the belief that a heavenly body existed near enough to Alvan Clark, of Boston (Mass.). discovered, on Jan. 31, 1862, what appears to be a planet revolving around Sirius as its sun, it is thought in about 49 years. The latitudes, and the procession of the equilatitudes, and the procession of the equiages. When the heliacal rising of Sirius (called by the old Egyptians Sothes) took SIROCCO place, it indicated to them that the overflow of the Nile was at hand.