This month, I’d like you to find the celestial ghoul’s head and watch for its “evil eye” to wink. I’m referring to Algol (Beta [β] Persei), the most enchanting naked-eye variable star in the night sky. To follow its changes, you need nothing more than your unaided eyes. But despite the star’s visibility, catching it at minimum light can be tricky, unless you know when to search it out. First, though, let’s look at a bit of interesting history. Astronomy magazine subscribers can read the full column for free. Just make sure you're registered with the website.