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Galactic Search

August 4, 2010

Like the downtown of a great city, the hub of the Milky Way galaxy is crowded and busy. Stars are packed elbow to elbow, and they're surrounded by enormous clouds of gas and dust, and by powerful magnetic fields. The question is, is anyone there to enjoy the show?

Astronomers have been using a radio telescope in California to try to find out. Last year, they surveyed a large patch of sky that includes the center of the galaxy. They hoped to hear radio "beacons" operated by other civilizations.

The survey was conducted with the Allen Telescope Array -- a collection of 42 antennas that are linked together to make a single telescope. It didn't look at any region of the sky long enough to hear ordinary radio signals, like the ones we Earthlings beam into space every day. But it was sensitive enough to detect powerful beacons that could be used to attract attention. And there were a lot of stars in its search area -- about 40 billion of them between us and the galactic center.

No artificial signals were detected. But more-sensitive searches could yet reveal whether anyone lives in the Milky Way's crowded "downtown."

That downtown is in Sagittarius, which scoots low across the south on August nights. Its brightest stars form the shape of a teapot. The subtle glow of the Milky Way rises from the spout like steam. The center of the galaxy is immersed in that steam -- 27,000 light-years away.

More about Sagittarius tomorrow.

Script by Damond Benningfield, Copyright 2010

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