Mark your calendars folks! Next Wednesday, starting at around 8:43PM EST, a total lunar eclipse will occur over the Americas. The next one is not due until December 2010, so if the sky is clear, get your derrière up from your computer chair and head outside to observe this rare phenomenon.

A lunar eclipse happens when the Moon passes through the shadow of Earth. You might expect the Moon to grow even more ashen than usual, but in fact it transforms into an orb of vivid red.

Why red? That is the color of Earth’s shadow.

[Via NASA]