Why does Algol

Why does Algol’s brightness vary? Algol has an unseen smaller and fainter companion star which orbits it. Every 2 days and 21 hours the smaller star passes in front of the brighter star causing part of the brighter star’s light to be blocked from us. It is at such times that Algol appears to dim.

In between Perseus and Cassiopeia is a beautiful sight for binoculars, the famous Double Cluster. These two closely situated open clusters are well worth a look.

To the south of Perseus and east of Andromeda is the small constellation Triangulum, The Triangle. Meanwhile, to the southeast of Triangulum is the equally small Aries, The Ram. Below both is the eastern end of Pisces.