The giant red star Betelgeuse has been getting dimmer and dimmer since Oct. 2019, and we don’t know why. The most exciting possibility is that it could be about to explode in a supernova explosion – but that’s not the most likely explanation.
Betelgeuse does vary in brightness, so getting dimmer is not that unusual. But it’s currently the dimmest it has ever been. Where normally it’s one of the top ten brightest stars, now it’s not even in the top 20. But that doesn’t necessarily mean it’s going to explode.
There are different events that sometimes cause Betelgeuse to get dimmer, and if more than one of them were to happen at the same time, it could cause the star to get unusually dim. That would be rare and unlikely, but probably more likely than a supernova explosion.
If it were to go supernova, it would light up the sky as brightly as the Moon, and could be seen even during the day for weeks. It would also permanently change the constellation Orion, because Betelgeuse makes up Orion’s shoulder. Instead of a star, that shoulder would be marked by a slowly expanding ring – a nebula. Again, this probably won’t happen any time soon. But whenever it does, it’ll be spectacular.
(Note: The header image – comparing a brighter Betelgeuse from a few years ago, left, to a much dimmer Betelgeuse last month, right – was generously shared with LSC by space photographer Brian Ottum).
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