How to find the Pleiades, and what a star count says about your sky
Look east-northeast a couple of hours after dark this week and you’ll find a small, tight knot of blue-white stars climbing out of the horizon haze. Most people take it for a smudge the first time they see it, and some take it for the Little Dipper. That’s the Pleiades, the Seven Sisters, Messier 45, and from now until spring it’s the easiest star cluster in the sky. You need nothing but your eyes to find it. Once you have, it doubles as a dark-sky test: count how many stars you can pick out of the knot and you have a rough reading of how good your sky is that night. ...