Betelgeuse, one of the brightest stars in the constellation Orion, began its dimming in October last year and reached its dimmest record in a century subsequently. A group of astronomers conducted an in-depth study about this phenomenon and published a research paper in August this year to explain the mystery of Betelgeuse's dimming.

The research team made use of the observational data on Betelgeuse in the past few years from the Hubble Space Telescope, including the analysis of its ultraviolet spectrum. They found that a large amount of hot material was moving from the surface of Betelgeuse to its outer atmosphere during September to November in 2019. The material finally left Betelgeuse, cooled down to form dust cloud and blocked some of the light emitted from Betelgeuse towards the Earth, causing the dimming effect we observed on the star.

Astronomers have long known that the brightness of Betelgeuse is always changing, but this unexpected dimming provoked speculation on whether Betelgeuse was about to experience a supernova explosion. The result of this study eliminated such speculation and revealed other stellar physics mechanism. Betelgeuse has already restored its expected brightness in April this year.