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See The Winking ‘Demon Star’ In Night Sky This Week
The star, known as Algol, is located in the constellation of Perseus, the Hero, and has been known since ancient times as “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. According to the myth, gazing at Medusa could turn a person to stone.
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, so the star’s whole performance can be watched in a single night when the schedule fits right. [Top 10 Star Mysteries]
17th Century Discovery
It appears that the first astronomer who definitely noticed Algol’s periodic dimmings was Geminiano Montanari of Bologna, around the year 1667.
At that time the only other known variable star was Mira, in the constellation of Cetus, the Whale. But, Mira’s light varies over a span of many months, whereas Algol’s light appears to vary over a span of just hours. Perhaps this is why few other astronomers paid much attention to Montanari’s discovery.
Algol’s variability was rediscovered in 1782 by the English amateur astronomer John Goodricke, an 18-year old deaf mute. Goodricke watched the star systematically and ultimately determined its period. It was also Goodricke who suggested the correct reason for the variations. Unlike Mira, whose brightness varies because it shrinks and swells, a large dim body orbits Algol, periodically blocking much of its light from our view.
