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March 18, 2011

The full Moon climbs high across the sky tonight, casting a chilly glow on the penultimate night of winter. It's a beautiful sight, but one with a downside. The moonlight overpowers the view of many of the stars, leaving only the brightest to shine through.

Among those are two that form a wide triangle with the Moon tonight: Regulus, which is well above the Moon as darkness falls, and Denebola, a little closer to the Moon's left. Both are in the constellation Leo -- Regulus at the lion's heart, and Denebola at its tail.

Denebola's a fairly close neighbor as stars go -- only about 36 light-years away. Even so, the fact that we can see it at all means that Denebola is quite bright -- more than 10 times brighter than the Sun.

Denebola's brightness is a product of its mass. The star is about twice as heavy as the Sun, so it "fuses" the hydrogen in its core at a much faster rate. That makes the star's surface thousands of degrees hotter than the Sun's. The combination of high temperature and large size makes Denebola outshine the Sun and all but a few percent of all the stars in the Milky Way galaxy.

Denebola is surrounded by a disk of dust grains. It may be supplied with fresh material by collisions between small planet-building bodies. So far, no one has seen any evidence of planets around the star, although they can't be ruled out, either. Astronomers continue to hunt for companions to our bright stellar neighbor.


Script by Damond Benningfield, Copyright 2011


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