A near-perfect alignment of the sun, the moon and Earth will provide sky watchers a generous holiday gift on the night of December 20 and the morning of December 21. If they can stay up late enough, North Americans should be able to witness—weather permitting—a prolonged total lunar eclipse, the first since February 2008. A lunar eclipse is among the most accessible astronomical phenomena to view: no telescope, binoculars or special eyewear needed.

The full moon will begin to slip into the northern half of Earth's shadow at 1:33 A.M. (Eastern Standard Time) on December 21, and by 2:41 A.M. the entirety of the moon should be subsumed, according to a NASA Web page about eclipses. That phase of the eclipse, known as "totality," will last 72 minutes, with the moon just beginning to edge out of shadow at 3:53 A.M.

The eclipse should be visible throughout North America, according to NASA, as well as in parts of western South America. The next time Earth blankets the moon in shadow, in June 2011, the Americas won't be so lucky, as the Western Hemisphere will mostly be turned away from the event. That eclipse will be most visible in Africa, Australia, the Middle East, and parts of Asia and Europe.

Photo credit: Steev on Flickr via Wikimedia Commons