penumbra and antumbra

Look Up! It’s the Snow Moon Lunar Eclipse Comet Spectacular

Last year it was all supermoons, all the time. This year it’s going to be eclipses. There’s the big one on August 21—start planning your trip now!—and leading up to it are a couple of smaller events, starting with a penumbral lunar eclipse tonight, and an annular solar eclipse later this month. The eclipse tomorrow night, February 10, will occur during a “Snow Moon,” and if you stay up a little bit longer, you might even be able to spot a comet. In other words, if you’re looking for cheap date ideas for the last Friday before Valentine’s Day, you’ve come to the right place.

Full moons have names. They survive largely through the pages of the Farmer’s Almanac, a 99-year-old annual best known for its weather predictions. You might recall the Hunter’s Moon, or the Harvest Moon, and who could forget the Beaver Moon?

Tonight’s moon is called the Snow Moon, named by the American Indians for the obvious reason: February is the snowiest month. (This moon was also sometimes called the “Hunger Moon,” for the same reason, and the “Shoulder to Shoulder Around the Fire Moon.”) Generally speaking, you get only one full moon per month. In fact, the word “month” is derived from “moon,” referring to a full cycle of its phases. Next month is the Worm Moon, because with the onset of spring, you have the wormiest month. And so on.

If you decide to have a moonlit picnic with your sweetheart, that kind of trivia is solid gold.

So what of this eclipse business? You might notice also that the moon seems a little … off. I don’t…