Illustrations based on data from the Hubble Space Telescope (HST) of a potential mechanism for the dimming of the red supergiant star Betelgeuse. The star suddenly became dimmer for several months during late 2019 and early 2020. The first two panels show a large ball of plasma being ejected from a huge convection cell on Betelgeuse's surface, as seen in ultraviolet light observations from the HST. In the third panel, as the expelled gas expands outwards, it cools to form an enormous dark dust cloud. The fourth panel shows how, when viewed from Earth, the dust cloud blocks light from a quarter of the star's surface, causing it to appear dimmer.