Dusty Skies

StarDate: January 20, 2009

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If your fireplace mantel, the top of your refrigerator, and the hood of your car could all pass the "white glove" test, then today's program probably isn't for you. If not, then listen up. Mixed in with the particles of dirt, the dead skin cells, the pollen grains, and the bug parts, the dust that accumulates on every surface includes bits of debris from beyond Earth.

Cosmic dust is born in the outer atmospheres of stars, or in the cold environs of space. Atoms of carbon, oxygen, and other elements bond together to form solid particles. These particles merge to form larger grains.

In our own solar system, lots of these grains came together to make the planets, moons, and other solid bodies. Some of the grains remained free, though. And the supply is replenished when asteroids hit each other and chip off tiny bits of material, or when the icy surfaces of comets vaporize and release solid particles into space.

Earth sweeps up about a hundred tons of these particles every day. Many are so small that they take a long time to float to the surface. Others are released when larger chunks of material break up in the upper atmosphere.

The particles are found across the entire planet. They've been found in ancient layers of ice in the Antarctic, and bound inside blobs of minerals on the bottom of the ocean. And a few of them land right around you, forming part of that embarrassing layer of dust that you miss -- but your mother-in-law doesn't.

Script by Damond Benningfield, Copyright 2008

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

The one constant in the Universe: StarDate magazine

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