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Moon, Mars, and Regulus

April 30, 2012

The stars yield their secrets grudgingly.

Consider Regulus, the brightest star of Leo, the lion. It’s directly above the Moon as night falls this evening, with the planet Mars close to its left.

For most of human history, Regulus was no more than a bright point of light in the night sky. But it held a special place in human affairs because it lies along the Sun’s path across the sky. In ancient Persia, it was one of four “royal” stars -- the guardians of the night.

The first observers to look at Regulus with a telescope found that it’s a double star -- the bright star that we see as Regulus, plus a fainter companion. And in 1867, an astronomer found that the companion is also a double star.

About that same time, astronomers also got their first good measure of Regulus’s distance. And in the late 20th century, they got their first good measure of its size.

Not until a few years ago, however, did they get a really complete dossier on Regulus. It’s several times the size and mass of the Sun, and about 350 times brighter; it spins so rapidly that it looks like a squashed beachball; and Regulus itself has a small companion in a tight orbit -- a “dead” star known as a white dwarf.

Yet there’s a lot about Regulus we don’t know. Its age is a bit muddled, for example. The star itself looks young, yet the presence of the white dwarf suggests it’s much older. Even today, Regulus continues to guard its secrets.


Script by Damond Benningfield, Copyright 2012


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