Algol (Beta Persei) -- Eclipsing Variable Star in Perseus
The Winking Eye of Medusa
Perseus was the famous hero in Greek Mythology that slew Medusa and saved the beautiful
Andromeda from the Sea Monster. If you have not read the story, I am sure you have seen
Perseus’ heroic deeds in bad movies. One highlight of the story is always Perseus doing
battle with Medusa -- an evil creature with hair of live snakes and eyes that would turn
people into stone if they gazed upon her.
Perseus did well and earned himself a constellation in the night sky. He forever holds his
starry sword high over his head and in his other hand the head of the slayed Medusa. Even
in death, Medusa’s eyes could still turn to stone any who dared to look at her (Perseus kept
Medusa’s head in a bag and only pulled it out when he wanted to turn someone or some
creature into stone).
The second brightest star in the constellation Perseus is Algol which means “Demon’s Head”.
It marks the location of Medusa’s head or more specifically her eye. Algol is bright and is
visible without the need for a telescope or binoculars even from light-polluted skies.
But there is more – the star/eye blinks every 2 days, 20 hours, 48 minutes and 56 seconds.
It is a slow blink to be sure but the change in Algol’s brightness is significant and obvious.
No telescope is needed; the blink is easily noticed using your eyes only.
Algol is an eclipsing binary star where a large star is circled by a smaller/dimmer star. When
the dimmer star eclipses the brighter star, the wink occurs. Eclipsing binary stars are not
rare, but Algol is the most famous and the most dramatic without resorting to a telescope.
When it will blink next can be easily found online or in astronomy magazines.
A third additional star belongs to the Algol system and a fourth star is suspected, however
neither is involved in the eclipsing process.
If you take the time to research the times when Algol winks and go outside and watch the
event, I guarantee that it is safe – as far as I know no one has been turned to stone.