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New Moon

July 1, 2011

The Moon is Absent From View today. That's because it's "new" -- it's crossing the imaginary line between Earth and the Sun, so it's hidden in the Sun's glare. It'll return to view tomorrow evening as a thin crescent low in the west after sunset.

There are actually two reasons we can't see the new Moon. Not only is it immersed in the sunlight, but it's nighttime across the entire lunar hemisphere that faces our way. Nighttime means no sunlight to reflect back toward Earth.

But no sunlight doesn't mean it's completely dark -- far from it, in fact, because there's a full Earth hanging in the lunar sky.

Earth covers about 16 times as much area in the sky as the Moon does. And on average, the surface of Earth is about three times brighter than the surface of the Moon. So a full Earth shines about 50 times brighter than a full Moon, illuminating the lunar landscape as brightly as late twilight here on Earth.

And from any given point on the lunar hemisphere that faces Earth, our planet always hangs in the same spot in the sky. So over a month, you'd see Earth cycle from full to new and back again -- all without moving.

You would see some motion, though -- the slow drift of the clouds across the bright Earthly disk. And today, you'd see one other feature: a slightly dark smudge moving across the southern Indian Ocean and the tip of Antarctica -- the lunar shadow creating a partial solar eclipse -- a signature of the new Moon.


Script by Damond Benningfield, Copyright 2011


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