Total eclipse of the Moon

It's supposed to indicate the end of the world, the blood-red moon of a total lunar eclipse. But it's just the Sun, Earth, and Moon in a perfect line. It happened last night for many in the US and much of the northern hemisphere. It's the last one until December 2010.

And yes, it has to be a full moon: the Earth, the Moon, and the Sun have to line up just so for the lunar eclipse to happen. The Earth passes between the Moon and the Sun, leaving the Moon lit only by reddish sunlight refracted through the Earth's atmosphere. The Earth's shadow is, relatively speaking, much larger than the Moon's, so lunar eclipses are far more common and widely visible than solar eclipses, when the Moon passes between the Earth and the Sun. That case can happen only during a new moon.

There will be a total solar eclipse later this year, on August 1.