But researchers working with the Hubble Telescope now have a clearer picture, seeing superhot plasma unleashed from the star’s surface, cooling down in the outer layers of the atmosphere, and eventually turning to dust.“The resulting cloud blocked light from about a quarter of the star’s surface,” the European Space Agency said in a statement, adding that the star had since returned to its normal brightness.
“With Hubble, we see the material as it left the visible surface of the star and moved through the atmosphere, before dust formed, which made the star appear to be darkening,” said lead researcher Andrea Dupree of the Harvard-Smithsonian Center for Astrophysics in the United States.
“We were able to see the effect of a dense, hot region in the southeastern part of the star moving outward.”
The researchers, who were due to publish their results in The Astrophysical Journal, said they were unsure of the ultimate cause of the plasma rash.
Betelgeuse, almost 1,000 times the size of the Sun, is 725 light years from Earth, which means that the event the telescope witnessed occurred around the beginning of the 14th century.