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March 10, 2010

The king of the beasts springs high across the eastern sky this evening: Leo, the lion. Not only is Leo the king of the jungle, he's no slouch in the skies, either -- he's the 12th largest of the 88 constellations. And unlike most other constellations, Leo actually looks like its namesake.

The brightest and best-known star in Leo is Regulus, which marks the lion's heart. But the star at Leo's tail is no slouch, either. The star is Denebola -- an Arabic name that means "the tail of the lion."

Denebola is a close stellar neighbor, at a distance of just 36 light-years. That's about half the distance of better-known Regulus.

Denebola is a white star, which means its surface is somewhat hotter than that of our yellow Sun. Denebola emits about 14 times more light than the Sun does, so it produces as much light in one day as the Sun does in two weeks.

Denebola is hotter and brighter than the Sun because it's about twice as massive. That greater mass squeezes and heats the star's center, speeding up the nuclear reactions there.

But Denebola will pay a price for its splendor. Because it consumes its fuel faster, it will die sooner. It first will expand to become a red giant. Then it will cast off its outer layers, leaving only its small, hot core, known as a white dwarf. Denebola will then fade from view -- while the Sun continues to shine its light on Earth and the other planets of the solar system.

We'll have more about Leo tomorrow.

Script by Ken Croswell, Copyright 2010

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