Illustration of a dark gas cloud in front of the red supergiant star Betelgeuse. Betelgeuse is about eight million years old and on the verge of becoming a supernova. It is one of the largest stars currently known, with a radius around 1400 times larger than the Sun's. The star suddenly became dimmer for several months during late 2019 and early 2020. It is thought that a large ball of plasma was ejected from Betelgeuse's surface, which expanded outwards to form an enormous dark dust cloud, obscuring some of its light from Earth.