October skywatchers can look for Algol, a star in the constellation Perseus long known as the “Demon Star” or “The Ghoul,” according to NASA’s latest Night Sky Notes.
Algol becomes visible in the northeastern sky after 9 p.m. during autumn, alongside the constellations Cassiopeia and Andromeda. NASA suggests using Cassiopeia and Andromeda to locate Perseus, then using the star Almach as a guide to Algol.
The star’s “blinking” reputation has a scientific explanation. Algol is a triple-star system, and two of its stars orbit each other as an eclipsing binary. About every three days, the system dims from magnitude +2.1 to +3.4 as one star passes in front of the other.
NASA’s October roundup also points skywatchers toward Halloween-inspired celestial objects, including the Witch Head Nebula and the Jack-o’-lantern Nebula, a cloud of gas and dust shaped by a massive star.
