Explained: What is causing the supergiant star Betelgeuse to dim and change its shape?

Betelgeuse was born as a supermassive star millions of years ago and has been “dramatically” and “mysteriously” dimming for the last six months.

Using the European Space Organisation’s (ESO) Very Large Telescope (VLT), astronomers have noticed the unprecedented dimming of Betelgeuse, a red supergiant star (over 20 times bigger than the Sun) in the constellation Orion.

What has intrigued some astronomers is the fact that along with the dimming, the star’s shape has been changing as well, as per recent photographs of the star taken using the VISIR instrument on the VLT. Instead of appearing round, the star now appears to be “squashed into an ova” as per a New York Times report.

What is happening to Betelgeuse and why is it significant?

Betelgeuse was born as a supermassive star millions of years ago and has been “dramatically” and “mysteriously” dimming for the last six months. According to a report in Sky and Telescope, among the brightest night time stars, Betelgeuse ranks 10th, but by the last week of December 2019, its brightness had dimmed so low, that the star was ranked as the 21st brightest, “a remarkable decline — and a historic low.” The report suggests that while Betelgeuse’s behaviour is out of the ordinary, it doesn’t mean that an eruption is imminent since astronomers predict the star to blast sometime (supernova explosion, which is the largest explosion to take place in space) in the next 100,000 years or so. The report goes on to say that the star may re-brighten, “but you never know what surprises may still be in store. Stars do as they please and that’s half the fun”.