安魂曲超新星：目前为止已见到3次的超新星
2021年11月02日 SN Requiem: A Supernova Seen Three Times So Far Image Credit: NASA, ESA, Hubble; Data: S. A. Rodney (U. South Carolina) et al.; Image Processing: J. DePasquale (STScI) Explanation: We’ve seen this same supernova three times — when will we see it a fourth? When a distant star explodes in a supernova, we’re lucky if we see it even...