Arches Cluster

StarDate: September 25, 2009

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Our nearest stellar neighbor is more than four light-years away. And it's so faint that we can't even see it.

But if we lived inside a star cluster near the center of the galaxy, the night sky would be bursting with close neighbors. In fact, thousands of stars would crowd inside that four-light-year range.

This busy city of stars is known as the Arches Cluster. It's more than 25,000 light-years away, in Sagittarius. That's where the Moon appears tonight -- right above the teapot formed by the constellation's brightest stars. The cluster is near the Moon, but it's hidden from view by thick clouds of dust.

The cluster is close to the heart of the Milky Way. That region of the galaxy is packed with stars and clouds of gas and dust, so it's zapped by radiation and twisted by strong magnetic and gravitational fields.

The Arches is probably around two million years old, which means its stars are all infants. Many of them are big, heavy, and hot; the biggest is probably more than a hundred times as massive as the Sun. But the cluster also contains many more stars that are comparable to the Sun or even smaller.

So if any planets inhabit the cluster, their night skies are spectacular. Hundreds of stars shine like brilliant sapphires or diamonds, some of them almost painful to look at. And thousands more are a little more subdued, but impressive nonetheless -- lighting up the night skies of a crowded neighborhood.

Script by Damond Benningfield, Copyright 2009

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