Sagitta
in astronomy, the Arrow; a small northern constellation, one of the SAGO 48 ancient asterisms. It is situated between the hill of the Swan and Aquila, and is traversed by a branch of the Milky Way. A nebula in Sagitta was resolved by Sir William Herschel, in 1783, into a cluster of stars. In geometry, (1) the versed sine of an arc. (From the resemblance of an arrow standing upright on the string of a bow.) (2) The abscissa of a curve. In zoölogy, the sole genus of Chætognatha, with several species, found on the surface of the ocean all over the world. They are transparent unsegmented worms, about an inch long.
The genus presents analogies with both the Nematoidea and the Ammelida.
SAGITTARIUS (the Archer), in astronomy, the ninth sign of the zodiac, into which the sun enters Nov. 22. The constellation consists of eight visible stars. It is represented on celestial globes and charts by the figure of a centaur in the act of shooting an arrow from his bow.