Monday, September 10, 2012

Monday Moonbeams / Algol, The Demon Star

Hello! This week I'm expanding the Moonbeam column to include something that's happening in the night sky this week. I found this information on, right here. I hope you don't mind the astrology lesson!

"This week, skywatchers will have the chance to catch a winking 'demon star' in the night sky.
The star, known as Algol, is located in the constellation of Perseus, the Hero, and has been known since ancient times as Algol, The Demon Star.

Algol has a long and venerable history. Its name comes from the Arabic word al-ghul, which means female demon. But, contrary to popular belief, the name seems to have nothing to do with the star's behavior, but rather, is due merely to Algol's position marking the head of the Gorgon Medusa in ancient Greek mythology.

Algol is one of the most famous variable stars in the sky, and was the first of its kind to be discovered. It is a perfect example of an "eclipsing binary" star, which brightens and dims almost as regular as clockwork.
Best of all, Algol takes less than ten hours to go from its normal brightness down to its minimum light and then back to normal.

The first astronomer who definitely noticed Algol's periodic dimmings was Geminiano Montanari of Bologna, around the year 1667.

Algol is located approximately 93 light-years away. The bright component, Algol A, is about 90 times as bright as the sun. The eclipsing body, known as Algol B, is a subgiant star that is "dim" only in comparison to the bright star; it gives off about three times the sun's light.
Both stars are several times larger than the sun and their motions are almost, but not quite, in our line of sight to them.

At its brightest, Algol is 3.3 times brighter than it is at its dimmest point. The whole eclipse requires nine hours and 40 minutes, and it occurs every 2 days, 20 hours, 48 minutes and 56.5 seconds.

Algol requires only 5 hours to fade from maximum to minimum. The star is at minimum for about 20 minutes during the time it takes Star B to pass across Star A, and then in another 5 hours, Algol is seemingly back to its normal bright self again.
Two hours before the predicted minimum start checking Algol’s brightness; its fade-down will become increasingly apparent as the minutes tick by. Similarly, watch during the two hours following minimum for a distinct upturn in brightness." -Joe Rao /

Johannes Hevelius' Perseus from Uranographia / Public Domain
 For even more information from the article including a table of Algol's brightness and time zones check here.

I've loved the image of Medusa every since I saw Bernini's Medusa in Rome, Italy at the Capitoline Museum. I even made a snake headdress and dressed like Medusa for Halloween a few years ago. 

Bernini's Medusa via Wikipedia

The last 4 photos by me, Tonya Moore. Rome, Italy

Isn't she painfully gorgeous?! So if you're outside at night this week throw caution to the wind and look for Medusa winking at you! :)

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