| Home | Articles | Guide to Observing | Tour of the Constellations | Book Reviews |
A bit over from Cassiopeia is the constellation Perseus, which appears as two crooked lines of closely packed stars attached at a common point to form a cursive "V". Like its neighbor Cassiopeia, Perseus is located in the Milky Way.
The Greeks named this constellation after Perseus, the son of Zeus and Danae. Perseus had a typical ancient Greek childhood. He was placed in a box and tossed into the sea by a cruel grandfather, then was rescued by some fisherman. Although Perseus rescued Andromeda from sea serpents, his big adventure was with Medusa. Perseus was asked for Medusa's head as a wedding gift by King Polydectes, who was really in love with Perseus' mother Danae, and thought this would be a convenient way to get rid of her son. The reaction of King Polydete's bride to this was left unrecorded. Medusa not only had a scalp covered with snakes but her very glance turned people into stone. With some timely help form the gods Athena and Hermes, Perseus cut off the head of Medusa and brought it back to the wedding party of King Polydectes, where it turned all the guests into stone.
Medusa’s head is represented by the star beta Perseus and is also known as Algol. Algol is the most famous variable star in the sky. It usually has an apparent magnitude of 2.2. Every 2.867 days, Algol suddenly dims down to a magnitude of 3.5. The period of dimming and the subsequent period for Algol to resume its usual brightness together last about five hours. Algol consists of two massive stars, one of the slightly smaller than its companion, but much brighter. When we on Earth see Algol suddenly dim, the slightly larger and much dimmer star has moved into a position between the brighter star and us. Much of the brighter star's light is blocked and Algol appears to dim.
Algol has mythology of its own, none of it complimentary. Its full Arabic name is Ras al-Gul, the Ghoul’s Head. Algol has also been known as the Demon Star and the Blinking Demon. The Jews called it Rosh ha-satan, Satan's Head, while in the Talmud it is labeled Lilit, Adam’s legendary first wife and a demon. The Chinese name is certainly the most gory, "Tseih She", which means the Piled- up Corpses. Perhaps people in ancient times were uncomfortable with a star that refused to behave itself and shine with a nice steady brightness.