Archive for October 30, 2018

10/30/2018 – Ephemeris – Algol the spookiest star in the sky

October 30, 2018 Comments off

Ephemeris for Tuesday, October 30th. The Sun will rise at 8:18. It’ll be up for 10 hours and 16 minutes, setting at 6:34. The Moon, 1 day before last quarter, will rise at 11:53 this evening.

Not all the ghosts and goblins out tomorrow night will be children. One will be out every night because it’s a star. Its name is Algol, from the Arabic for Ghoul Star or Demon Star. The Chinese had a name for it that meant “piled up corpses”. It’s normally the second brightest star in the constellation Perseus the hero, visible in the northeast this evening. The star is located where artists have drawn the severed head of Medusa, whom he had slain. Medusa was so ugly that she turned all who gazed upon her to stone. Algol is her still glittering eye. The star got these names before astronomers found out what was wrong with it. They found out that it does a slow wink every two days, 21 hours.  That’s because Algol is two stars that eclipse each other. Her next evening wink will be dimmest at 8:10 p.m. November 13th.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.


Algol Finder
Perseus, Cassiopeia, Andromeda with Algol finder animation for Autumn evenings. Created using Stellarium and GIMP
Eclipsing Binary Star
Animation of an eclipsing binary star like Algol. Credit: Wikimedia Commons h/t Earth and Sky