Eclipse!

Tonight there will be a total eclipse of the Moon. Usually, at new and full moon, the Earth, Sun, and Moon are only approximately aligned. Tonight, however, that alignment is just about perfect. The Moon begins slipping into the outer shadow of the Earth at 8:43 P.M. When we see the curved edge of the Earth'ss shadow on the Moon, wešll really know that the Earth is round! (This was one of the first proofs that the Earth is round.)

During totality, beginning at 10:01 P.M., and ending at 10:51, the Moon will still be visible as a dull red disk, because of the sunlight bent by the atmosphere of the Earth.

It often looks like the full Moon, so close to the horizon, is much larger than the Moon at other times. But you can convince yourself that this is not true, and all you need to do it is you outstretched hand. Hold out your hand at arm's length. Just one fingertip should be enough to cover the Moon. Try this when the Moon is near the horizon and again when it is high in the sky. The Moon (and the Sun, too) seems only as big as your fingertip.

(02/20/08)