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August 5, 2010

Every star that's visible to the unaided eye has a long list of aliases. They're listed in several different star catalogs, and the brightest of them are designated with letters of the Greek alphabet. And the brightest of the bright also have proper names, usually bestowed many centuries ago.

As an example, consider the second-brightest star in the constellation Sagittarius, which arcs low across the south on summer nights. The star is at the top left corner of the "teapot" formed by Sagittarius's brightest stars.

The star's list of names includes Sigma Sagittarii and 34 Sagittarii, plus catalog listings SAO 187448, HD 175191, and more than two dozen others.

Its proper name is Nunki, and it may be the oldest star name that's still in use.

The name comes from a list of 30 stars from ancient Babylon. The name refers to the sea, perhaps because the star lies near the shores of a region of sky known as the celestial sea. Over the centuries, the name disappeared. But a few centuries ago, it was resurrected by European navigators, and it remains in use today.

Nunki is more than 200 light-years away from us. It looks so bright in our sky because it's much bigger, hotter, and brighter than the Sun. That flashiness means it will live only a tiny fraction as long as the Sun will. Even so, this star with an ancient name will continue to shine in Earth's night sky for millions of years to come.

Script by Damond Benningfield, Copyright 2010

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