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Ephemeris: 10/30/2025 – Algol, the perfect Halloween star

October 30, 2025 Comments off

This is Ephemeris for Thursday, October 30th. Today the Sun will be up for 10 hours and 15 minutes, setting at 6:33, and it will rise tomorrow at 8:19. The Moon, 1 day past first quarter, will set at 2:03 tomorrow morning.

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. 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 we knew what was wrong with it. 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 its dimmest at 10:12 p.m. Tuesday, November 4th.

The astronomical event times given in this blog are for the Traverse City/Interlochen area of Michigan (Lat 44.7° N, Long 85.7° W; EDT, UT – 4 hours) unless stated otherwise. Times will be different for other locations.

Addendum

Algol Finder Animation
Algol Finder Animation for around 8 pm in the later part of October and early November (7 pm after the EST time change on the first Sunday in November). Created using Stellarium and GIMP.
Eclipsing Binary Star
Animation of an eclipsing binary star like Algol. Credit: Wikimedia Commons h/t Earth and Sky
Categories: Ephemeris Program, Observing, Stars Tags: , ,