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Total Lunar Eclipse
A photo of the May 2003 lunar eclipse by Loyd Overcash of Houston, Tex.
A photo of the May 2003 lunar eclipse by Loyd Overcash of Houston, Texas.

By Dr. Tony Phillips
Science@NASA

According to folklore, October's full moon is called the "Hunter's Moon" or sometimes the "Blood Moon." It gets its name from hunters who tracked and killed their prey by autumn moonlight, stockpiling food for the winter ahead. You can picture them: silent figures padding through the forest, the moon overhead, pale as a corpse, its cold light betraying the creatures of the wood.

The Blood Moon rises this year on Wednesday, Oct. 27th. At first it will seem pale and cold, as usual. And then ... blood red.

It's a lunar eclipse. Beginning at 9:14 p.m. EDT (6:14 p.m. PDT), the moon will glide through Earth's shadow for more than three hours. Observers on every continent (map) except Australia can see the event: The pale-white moon will turn pumpkin orange as it plunges into shadow, becoming eerie red during totality.

What makes the eclipsed moon turn red? The answer lies inside Earth's shadow:

Our planet casts a long shadow. It starts on the ground--Step outside at night. You're in Earth's shadow. Think about it!--and it stretches almost a million miles into space, far enough to reach the moon.

Suppose you had a personal spaceship. Here's your mission: Tonight, at midnight, blast off and fly down the middle of Earth's shadow. Keep going until you're about 200,000 miles above Earth, almost to the moon. Now turn around and look down. The view from your cockpit window is Earth's nightside, the dark half of our planet opposite the sun. But it's not completely dark! All around Earth's limb, the atmosphere glows red.

What you're seeing is every sunrise and sunset on Earth--all at once. This ring of light shines into Earth's shadow, breaking the utter darkness you might expect to find there. Turn off the cockpit lights. There's a lovely red glow.

Lunar Eclipse Schedule Wednesday, October 27, 2004

Moon enters Earth's shadow totality begins totality ends Moon exits Earth's shadow
Universal Time 01:14 (Oct 28) 02:23 (Oct 28) 03:45 (Oct 28) 04:54 (Oct 28)
Eastern Time 9:14 p.m. 10:23 p.m. 11:45 p.m. 00:54 a.m. (Oct. 28)
Central Time 8:14 p.m. 9:23 p.m. 10:45 p.m. 11:54 p.m.
Mountain Time 7:14 p.m. 8:23 p.m. 9:45 p.m. 10:54 p.m.
Pacific Time 6:14 p.m. 7:23 p.m. 8:45 p.m. 9:54 p.m.
Alaska Time 5:14 p.m. 6:23 p.m. 7:45 p.m. 8:54 p.m.
Hawaii Time 3:14 p.m. 4:23 p.m. 5:45 p.m. 6:54 p.m.
That same red light plays across the moon when it's inside Earth's shadow. The exact color depends on what's floating around in Earth's atmosphere. Following a volcanic eruption, for instance, dust and ash can turn global sunsets vivid red. The moon would glow vivid red, too. Lots of clouds, on the other hand, extinguish sunsets, leading to darker, dimmer eclipses.

Why isn't the moon totally dark when Earth gets between it and the sun? It's because of Earth's atmosphere.

White light from the Sun is a mixture of all the colors of the rainbow. When a ray of "white" sunlight passes at grazing incidence through Earth's atmosphere, molecules and aerosols in the air scatter blue light in all directions (this is why the sky is blue). The remaining reddish light is bent (refracted) into Earth's umbral shadow zone, giving the eclipsed Moon a coppery glow.

How will the moon look on Oct 27th? Corpse white. Pumpkin orange. Blood red. Maybe all three. Step outside and see for yourself.

Warning: While you're staring at the sky, you might hear footsteps among the trees, the twang of a bow, a desperate scurry to shelter. That's just your imagination.


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Last Updated: 24 February 2011

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