Pulling her out and reviving her caused so much confusion, it wasn't until then that they discovered Algol had disappeared.
The most easterly one is β Persei, known as Algol, the famous variable.
It is for this reason that Algol varies in brightness in this period.
Algenib and Algol form with γ Andromedæ, a right-angled triangle.
This dark star sometimes comes between Algol and the observer and cuts off the light.
Mention has been made of a slight irregularity in Algol's period of variation.
Every third night Algol has its light reduced for several hours.
Mr. Gore thinks that the companion of Algol may be a star of the sixth magnitude.
Stars of this class are all very remote, and no attempt has as yet been made to ascertain the parallax of Algol.
It was first supposed to be of the Algol type, with a period of about two days.
Beta Persei, variable star in the constellation Perseus, late 14c., literally "the Demon," from Arabic al-ghul "the demon" (see ghoul). It corresponds, in modern representations of the constellation, to the gorgon's head Perseus is holding, but it probably was so called because it visibly varies in brightness every three days, which sets it apart from other bright stars. The computer language (1959) is a contraction of algo(rithmic) l(anguage); see algorithm.