The bright, red star Betelgeuse in the constellation Orion has shown some unexpected behaviour. In late 2019 and 2020 it became fainter than we had ever seen it – at least in records going back more than a century. Briefly it became fainter (just about) than Bellatrix, the third brightest star of Orion. This event became known as the “great dimming”.
But Betelgeuse has since become bright again. For a few days this year, it was the brightest star in Orion – brighter than we have ever seen it. Both events led to speculation about whether its demise in the form of an explosion is imminent. But is there any evidence to support this idea? And how would such an explosion affect us here on the earth?
Stars are, by and large, remarkably stable. They shine with the same brightness year after year. But there are exceptions and some stars – dubbed variable stars – change in brightness. Most famous is Mira, the “star of wonder”, which was discovered as a variable star by the German pastor David Fabricius in 1596 – it is a pulsating star which regularly expands and contracts.
