1911 Encyclopædia Britannica/Cetus
CETUS (“The Whale”), in astronomy, a constellation of the southern hemisphere, mentioned by Eudoxus (4th century B.C.) and Aratus (3rd century B.C.), and fabled by the Greeks to be the monster sent by Neptune to devour Andromeda, but which was slain by Perseus. Ptolemy catalogued 22 stars in this constellation; Tycho Brahe, 21; and Hevelius, 45. The most remarkable star of this constellation is ο-(Mira) Ceti, a long-period variable, discovered by the German astronomer Fabricius; its magnitude varies between about 3 to 9, and its period is 331 days. τ-Ceti is an irregular variable, its extreme magnitudes being 5 and 7; γ-Ceti is a beautiful double star, consisting of a yellow star of magnitude 3 and a blue of magnitude 6.8; ν-Ceti is also a double star.