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Galactic Melting Pot

July 6, 2010

We're heading into the best time of year to watch the Milky Way. Right now, it curves low across the eastern sky at nightfall -- from Scorpius and the teapot of Sagittarius in the south; to Cygnus, the swan, in the east; to W-shaped Cassiopeia in the north.

The Milky Way is the subtle glow of millions of stars that outline the disk of our home galaxy. But for some of those stars, the Milky Way is an adopted home -- the stars were born elsewhere, and scooped up by the Milky Way.

The Milky Way is a galactic giant -- a disk of stars, gas, and dust that spans more than a hundred thousand light-years. It grew so big in part through the mergers of smaller galaxies. And today, the Milky Way is so big and massive that it easily pulls in other galaxies and incorporates their stars.

It's digesting at least two smaller galaxies right now. One of them is beyond the stars that form the teapot of Sagittarius, on the other side of the galactic center.

Astronomers have found the likely remnants of several older galaxies, too. Each forms a long streamer of stars that loops through the galaxy. One of these streamers encircles the galaxy's rim.

And many of the giant star clusters that loop outside the galaxy's disk may be remnants of other galaxies, too; we'll have more about that tomorrow.

All of these adopted stars make the Milky Way a galactic melting pot: a home for lots of stars that immigrated into our giant home galaxy.

Script by Damond Benningfield, Copyright 2010

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