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April 26, 2011

Because we live inside our home galaxy, the Milky Way, we don't know exactly what it would look like if we could view it from afar. But it probably resembles the galaxy known as M83 -- a beautiful spiral that's 15 million light-years away in the constellation Hydra.

M83 is part of a large collection of galaxies known as the Centaurus Group. It takes its name from French comet hunter Charles Messier -- the "M" in M83 -- who catalogued the galaxy in the 1700s.

Like the Milky Way, M83 is a barred spiral galaxy. Its brightest stars outline a beautiful pinwheel, while its central region consists of an elongated bar of stars.

Both M83 and the Milky Way give birth to new stars. The stars are born in giant clouds of gas and dust that reside in each galaxy's starry disk. Encircling the starry disk is another disk, made mostly of hydrogen gas. This remote gas is much more thinly spread than the gas that normally creates new stars.

Recently, though, astronomers detected signs of star formation in this remote disk in M83. In fact, some stars are being born more than 100,000 light-years from M83's center.

So few new stars are forming in M83's outskirts that astronomers estimate it'll take a hundred billion years -- far longer than the age of the universe -- to use up this distant gas. Still, the discovery suggests that the boondocks of M83 -- and by extension, our own Milky Way -- are more lively than astronomers had thought.


Script by Ken Croswell, Copyright 2011


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