Betelgeuse is a red supergiant star, one of the largest visible to the naked eye. It is usually the tenth-brightest star in the night sky and the second-brightest in the constellation of Orion. It is a semiregular variable star with an apparent magnitude varying between +0.0 and +1.6. It has the widest range of brightness displayed by any first-magnitude star.

Beginning in October, 2019, Betelgeuse began to dim noticeably, and by February, 2020, its brightness had dropped from magnitude 0.5 to 1.7, a factor of 3. It then returned to more normal brightness by April, 2023. Observations using the Hubble Space Telescope suggest that dust created by a surface mass ejection was the cause of the unusual dimming.

The image above show Betelgeuse surrounded by a clumpy envelope of material in its immediate vicinity. It was taken by the Herschel Space Observatory in 2013.

Image Credit: ESA