SAGITTARIUS ("the archer"), in astronomy, the 9th sign of the zodiac (q.v.) denoted by the symbol ♐︎, an arrow or dart. It is also a constellation, mentioned by Eudoxus (4th century B.C.) and Aratus (3rd century B.C.), and catalogued by Ptolemy, 31 stars, Tycho Brahe 14 and Hevelius 22. The Greeks represented this constellation as a centaur in the act of shooting an arrow, and professed it to be Crotus, son of Eupheme, the nurse of the Muses. Several short period variables occur in the constellation, e.g. X3 Sagittarii, Wγ1 Sagittarii and Y Sagittarii, having periods of 7.01, 7.59, 5.77 days respectively. Nova Sagittarii is a "new" star, which was discovered by Mrs Fleming in 1899; the nebula M. 17 Sagittarii is an omega or horseshoe nebula, while the nebula and cluster M. 8 Sagittarii is a splendid irregular nebula associated with a great number of faint stars.