While children dress up as ghosts and goblins for halloween and get their bags and orange plastic pumpkins filled with candy, there's a ghoul in the night sky above and it's called Algol, the Demon ...

These photos contrast the star Algol at normal brightness (left) and when it's eclipsed by a close companion star 2.9 days later. Algol is located in the constellation Perseus, which is shaped liked a ...

In this artist's view, the larger, cooler star in the Algol pair deeply eclipses the smaller, brighter star every 2.9 days. We can easily see the eclipse as a dramatic change in Algol's brightness.