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.
SHOULDER TO SHOULDER WITH THE SNOW MOON
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.
THE SOFTER SIDE OF A LUNAR ECLIPSE
So what of this eclipse business? You might notice also that the moon seems a little … off. I don’t want to get your hopes up here: You will not see a Pacman-like chomp taken out of the moon, nor any well-defined line that you can point at and say, "See that? That is the edge of the Earth’s shadow."
Penumbral eclipses are a bit subtler than that. What you’ll want to look for is a darker hue to pass across the lunar surface. That’s it, but it’s still really cool. What’s happening is this. Shadows have two elements: the umbra and the penumbra. The umbra is the darkest part of a shadow. (The red super harvest moon in 2015 was caused by the Moon passing into the umbra of the Earth’s shadow.) The penumbra is the much gentler, much blurrier shadow that surrounds the umbra. It’s the place where the light source (in this case the Sun) is partially blocked, but not entirely. That’s the part of the Earth’s shadow that the Moon will be passing through tonight. As long as you keep your expectations in check, you should enjoy the show.
(There’s also the antumbra, in which the object being shadowed is fully contained in the light source—we’ll talk more about that on February 26, when the Moon as seen from the Southern hemisphere will become a giant, terrifying ring of fire.)
If you live in North America, you can watch the penumbral eclipse on February 10 at precisely 7:43 p.m. EST.
THE TEAL COMET NEAR HERCULES
There will also be a comet out for your pre-Valentines Friday date night viewing pleasure. Its full name is Comet 45P/Honda-Mrkos-Pajdušáková, but its friends call it "45P." It will be visible around 3:00 a.m. EST. This particular comet visits us every five years, and tonight is its closest approach to Earth in its orbit. You’ll be gazing in the vicinity of the constellation Hercules, and looking specifically for a teal dot with a tail.
Realistically speaking, though, will you be able to see it? If the light pollution in your area is nil, and if your eyes are well adjusted, there’s a very slim chance you’ll be able to spot it with your naked eyes. I would not risk a disappointing end to a date night, however. After checking out the eclipse, head inside where it’s warm and go to Slooh. At 10:30 p.m. EST, astronomers will begin coverage of the comet, and use telescopes to give you a much better view than you’ll find in the backyard. If you have a fireplace, all the better for setting the mood. It is a Shoulder to Shoulder Around the Fire Moon, after all.