Betelgeuse lost 40% of its brightness. A weather satellite caught it.

Between October 2019 and February 2020, Betelgeuse — one of the brightest stars in the sky, the orange shoulder of Orion — dropped roughly 40% in visual brightness, its faintest recorded magnitude in modern observation history. Astronomers pointed every instrument they had at it; the internet asked if it was about to go supernova. The most complete light curve came from an unlikely source: Himawari-8, a Japanese weather satellite built to track typhoons, which happened to have Betelgeuse in its field of view. The leading explanation combines a cooling photosphere with a Surface Mass Ejection — a stellar-scale coronal mass ejection — condensing into a dust veil. Betelgeuse recovered by mid-2020, and was running unusually bright by 2023.