27 Oct 2011

Perseus holds the head of Medusa, whose eye is marked by Algol, the "Demon star." (Credit: Stellarium.org)

A star perfect for Halloween currently lies in the northeast evening sky within the constellation Perseus. It’s Algol—the “Demon Star”—and it represents the eye of Medusa.

According to myth, if you looked at Medusa you’d turn to stone. Perseus managed to chop off Medusa’s head by looking only at her reflected image in his shield.

Algol looks like a single star to us, but it’s actually a multiple star system. From our point of view on Earth, two of the stars in the Algol system orbit each other such that one star periodically passes in front of (eclipses) the other, blocking its light.

When the light from this “eclipsing binary” dims every few days, you can imagine it as the eye of Medusa, still winking after the head has been cut off.

Head of Medusa

Sorry, but you've just been turned to stone.

If you’d like to hear the full story of Perseus and Medusa along with other tales of madness, murder, and mayhem in the night sky, please join Morehead Planetarium and Science Center for a special edition of our live planetarium program Carolina Skies.  In honor of Halloween, we will have several “Scare-olina Skies” shows:

  • Adult versions: Scare-olina Skies shows on Saturday night, October 29, 2011 (at 7:00 p.m. and 8:30 p.m.) feature themes designed for adults and older teens.
  • Family-friendly version: Scare-olina Skies on Sunday, October 30, 2011 (at 3:30 p.m.) is designed for children ages 5-12 and their families.

Watch out! Medusa will make an appearance on the planetarium dome during Scare-olina Skies.



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