“Mystery solved”: But dust cloud responsible for the darkening of Betelgeuse


A team of astronomers said they had solved the mystery of the unusually strong darkening of Betelgeuse a year and a half ago. According to this, a cloud of dust was responsible, which had partially covered the striking star from our perspective. According to their analysis, the star had emitted a “mighty gas bubble” that was moving away from it. When part of the star’s surface cooled down afterwards – which is not unusual with Betelgeuse – that was enough to let this gas condense into solid dust. Accordingly, the darkening was a direct result of the formation of stardust.

Betelgeuse’s position in the constellation Orion

(Image: ESO / N. Risinger (

Betelgeuse is the shoulder star of the constellation Orion and is actually one of the brightest in the night sky. At the end of 2019, however, it had slipped significantly in this ranking, some astronomers had pointed out that it was a “red supergiant” that had reached the end of its star life. That is why there was some speculation about an imminent supernova, although this prognosis was based on astronomical periods.

In October 2020, a research team confirmed that Betelgeuse would still have around 100,000 years until the final explosion in a supernova. The team had also determined that the star is closer to us than previously thought. Before that, gigantic star stains had been blamed for the darkening.

(Source: ESO / L. Cal├žada)

The now in the trade magazine Nature presented study on the cause of the mysterious blackout is based on images from the Very Large Telescope (VLT) of the European Southern Observatory (ESO). They show the surface of the star – which is one of the few in the night sky that cannot just be resolved as a point – as it darkens. The now published images show the unevenly darkening star and then a significantly lighter spot on its surface.

Their analysis also confirmed that the end of Betelgeuse is not imminent, add to them. Stardust, as it was created during the event, could later become the building blocks of planets and life – we too are made of it.


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