There aren't many reasons to wake up at a quarter of 5 a.m., but tomorrow's celestial phenomenon—a total lunar eclipse—may be one of them. The second of 2007, tomorrow's eclipse will be but a fleeting treat for Washington and the rest of the eastern U.S. According to the U.S. Naval Observatory's friendly and helpful public affairs Officer, Geoff Chester, Washington will be lucky enough to see the Moon slip into the Earth's umbral shadow a little more than a half hour before it sets in the pre-dawn hours.

At 4:51 a.m. tomorrow morning, the Moon's eastern limb (its left edge) will begin to enter the Earth's shadow. About ten or 20 minutes before this, the Moon will be in the Earth's penumbra. Chester says the Moon will take on a "subtle gray shade" during this time, but you'll have to look close to see it, as the Earth's penumbra is very diffuse. Between 4:51 and 5:52 a.m. is the period of the Moon's partial eclipse, and at 5:52, totality begins. The Moon will start slipping below the horizon as this happens, and will be in total eclipse until moonset at 6:27 a.m.

Photo of March 2007's lunar eclipse from philliefan_99.

Chester says that the unknown aspect of every lunar eclipse is what color the Moon will be during totality. "The color of the eclipse if fairly unpredictable. It's the effect of the opacity of the Earth's upper atmosphere," says Chester. He said that, since the Moon will be moving through the shadow of the southern hemisphere, it will probably be a little lighter, "There is more ocean in the southern hemisphere, so the air will be less dirty."

The Moon will set a little south of west, so observers should look right on the western horizon for the eclipse. Chester recommends high spots with a clear line of sight into the southwestern sky for the best views. "Maybe Ft. Reno or some other unobstructed view," he says, "make sure you're not looking into Rosslyn." Chester notes that for those of you who don't want to get up so early, the next total lunar eclipse in Washington will take place on February 20th, 2008, beginning at 8:42 p.m. and reaching its greatest point just before 10:30 p.m. It might be cold then, but it will certainly be worth it since the next one after that won't occur until December 21, 2010.

Intrepid photogs might want to check out this page of tips for lunar eclipse photography. Does anyone plan to head out tomorrow morning to check it out? Let us know in the comments.