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Moon and Betelgeuse

November 16, 2016

Betelgeuse is one of the biggest and brightest stars in our galactic neighborhood. But the bright orange shoulder of Orion the hunter hasn’t always been such a monster. In fact, it may have reached its current state as recently as 10,000 years ago — the blink of an eye on the cosmic timescale.

Betelgeuse probably was born about 10 million years ago. It was much more massive than the Sun, which made it extremely hot and bright. And it may have had a companion that was even more impressive than Betelgeuse itself.

About a million years ago, the companion exploded, giving Betelgeuse a swift “kick” across the galaxy.

By then, changes in its core were causing Betelgeuse to get bigger and brighter. It became a blue supergiant similar to Orion’s other leading light, Rigel. And not long ago, it got even bigger, causing its outer layers to turn cooler and redder. Today, it’s probably more than a thousand times the diameter of the Sun.

Over the next few hundred thousand years, Betelgeuse may expand even more. Then it may briefly contract, once again turning blue. And that’ll set the stage for its final act: It will blast itself to bits as a supernova. For a while, it may shine as brightly in Earth’s sky as the full Moon — an impressive end for an impressive star.

For now, look for Betelgeuse to the right of the gibbous Moon as they climb into good view by around 9 o’clock. They stick close together for the rest of the night.


Script by Damond Benningfield

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