Monday, August 06, 2007

Sky Dragon Swallows the Moon

Sky Dragon Swallows the Moon
by Dave Adalian

In the early morning hours of Tuesday, Aug. 28, the Moon will be swallowed by a great sky dragon that will slowly consume it, turning the lunar disk a deep blood red.

The Moon will not sit well on the dragon’s stomach, and 90 minutes later it will escape back into the sky to the thunderous noise of exploding firecrackers, the clash of pots and pans and the hoarse and angry screaming of humans shouting to frighten the hungry dragon away.

At least that’s the way it would happen if this were ancient China. If we were among the Vikings, it would be pretty much the same thing, with a wolf eating the Moon instead of a dragon. For the Serrano Indians, it’s the spirits of the dead doing a bit of celestial binging and purging.

The reality isn’t nearly so fanciful, but it’s at least as dramatic.

Usually once or twice a year--but sometimes thrice or even not at all--the Earth, Moon and Sun will for a brief few minutes line up so Earth’s shadow falls across the Moon, nearly blotting it from the sky. But, because Earth’s atmosphere bends some of the sunlight, the shadow is never completely dark, giving the Moon a red or brown tint during totality.

On the morning of Aug. 28, the Moon will begin to darken at a few minutes before 1 a.m., as it enters Earth’s penumbra, the lighter ring of shadow surrounding Earth’s darker inner shadow, the umbra.

Just moments after the Moon is entirely within the penumbra, a minute or two after 2 o’clock, its leading edge will enter the darker umbra and begin to take on the ruddy aspect of blood.

For almost an hour the Moon will fall deeper into the umbra until by 3 a.m. it will be entirely consumed by darkness.

The only way out for the Moon is through, a journey that will take some 90 minutes to complete. The Moon will reemerge beginning about 4:25 a.m., exiting the umbra entirely an hour later.

The Moon will still be in the lighter penumbral shadow for another hour, finally escaping Earth’s shadow into the pale blue light before dawn, only a scant few minutes before the Sun rises on the opposite side of the sky and the Moon sinks into the west.


This column appeared originally in the Visalia (Calif.) Times-Delta and Tulare (Calif.) Advance-Register on Aug. 23, 2007.


For a more technical discussion of the Aug. 28, 2007 lunar eclipse, along with charts and times, visit NASA's Eclipse Home Page.