The Moon Goes Red Tonight
Are you in North America? Do you like staying up late and staring up at the sky? Yes? Then I have good news!
You can catch a total lunar eclipse Monday night, in all of its dusty-red glory, from just about anywhere in North America with a clear view of the night sky. The moon will enter the darkest part of Earth’s shadow (the “umbra”) at 1:58 AM ET, and remain there until 4:24 AM ET. At 3:06 ET, the moon will be completely darkened by the Earth’s shadow!
Except that the moon won’t be completely dark. During a lunar eclipse, the moon turns a dusty shade of red. Why is that? You can thank Earth’s atmosphere.
To understand the red color of a lunar eclipse, it’s best to see how Earth would look from the moon. Check out this shot of Earth eclipsing the sun taken by Apollo astronauts:
See that halo of light around Earth? Our diffuse shell of air and dust bends and reflects a portion of the eclipsed sun’s light around the planet and onto the obscured moon. And since only the longest wavelengths of light make it through our atmosphere without being scattered away by the air molecules (the same reason that sunsets are red), the moon is bathed in crimson! Here’s a video I made about that atmospheric color show.
Check out more eclipse goodness at Bad Astronomy. Top image via Wikipedia.