If you look up in the sky, you might be able to find Orion, one of the most recognizable constellations. There’s been an ongoing mystery in that patch of space involving Betelgeuse, one of Orion’s “shoulders”, and a humongous, bright red star nearing the end of its life. For some inexplicable reason, when astronomers observed it in February 2020, it was far fainter than it should have been.
Known as Betelgeuse’s Great Dimming, the star appeared only ¼ to ½ as bright as usual, a much bigger change than usually observed in any normal star. For an old supergiant star like Betelgeuse, this is suspicious — astronomers first thought that this change could be a harbinger of the star’s death, an indicator that it might explode into a supernova soon. But new research published in Nature just uncovered the true culprit behind the dimming: dust.
Although this is less dramatic than stellar death, dust is an important and sometimes pesky part of astronomy. The whole universe is filled with it, it’s key to so many processes in space, and it often gets in the way of astronomical observations. Old supergiant stars like Betelgeuse are known to eject gas as they pulsate, which can form dust clouds around them. The new observations of Betelgeuse show that dust ejected from a cooler patch of the star shrouded the star’s southern hemisphere, producing the dimming scientists observed last year. This whole ordeal has provided great insight into how the biggest stars age and die.
So while the Great Dimming was not, in fact, a signal of the star’s imminent death, that doesn’t mean Betelgeuse is guaranteed not to explode anytime soon. And when it does, it’ll surely be a grand show in the night sky.