On Sunday, May 20, observers along a narrow line throughout the western United States will be able to see the Sun, the Moon, and Earth line up. Unfortunately, the Moon will be near its farthest point from Earth, so it won’t totally cover the Sun’s disk. At mideclipse, a ring of sunlight still will be visible. Because the Latin word for “ring” is annulus, we call this type of eclipse an annular eclipse. You can read all about this event in the Astronomy.com News section and in the May 2012 issue of Astronomy.
The antumbra is the region past where the Moon’s shadow converges. Anyone under the antumbra will see an annular eclipse. // Illustration by F. Espenak (NASA/GSFC)
I’m blogging about it because, as luck (by which I really mean great planning) would have it, I’ll be in northern Arizona with at least 16 of my closest friends partying under the Moon’s shadow. Well, its “dissolved” shadow, as I like to say. There is a shadow, but you can’t see it because of that annoying ring of sunlight still visible. NASA’s eclipse guru Fred Espenak calls it the “antumbra,” which makes a lot of sense. The dark central part of the Moon’s shadow (the umbra) doesn’t quite reach Earth. Anything after the point at which the shadow converges, according to Espenak, is the antumbra.
Astronomy’s other senior editor, Rich Talcott, is already leading the magazine’s official annular eclipse tour. So, about six months ago, I called a couple friends and asked them if they’d be interested in an informal get-together under the Moon’s shadow — uhhh, antumbra.
After the first few “you bet” replies, I called a couple more friends. Then several of them asked if they also could bring friends and relatives. “Sure,” I said, thinking, “This is turning into a real party.”
Anyway, it turns out that, because of our respective locations, my phone and Internet access probably will be better than Rich’s throughout eclipse weekend. So watch for my blogs (including images, I hope) and tweets before, after, and probably during, the event.