The last total lunar eclipse until December 20, 2010, will thrill observers throughout North America February 20.

"This eclipse is perfect for getting the family together," Astronomy Senior Editor Michael Bakich says, "because it begins early in the evening."

On February 20, eclipse observers should plan to get out lawn chairs, binoculars, and low-power eyepieces. And, this year, better add a blanket.

A lunar eclipse occurs when the Moon, in orbit around Earth, passes into Earth's shadow. Because the Sun isn't a point of light, the shadow has two parts — the inner, darker umbra and the outer, lighter penumbra. If the whole Moon enters the umbra, the eclipse is total. If the umbra hides only part of the Moon, the eclipse is partial.

The eclipse's umbral phase begins at 8:43 P.M. EST. On the East Coast, the Moon already stands one-third of the way up in the eastern sky. For West Coast observers, the Moon rises minutes after the umbra touches its surface.