On Sunday and Monday, those in the Western Hemisphere with clear skies were fortunate enough to see the last total lunar eclipse of the decade. As the moon took on a distinctly redder shade just before midnight Eastern Time, livestreams of the phenomenon showed a flash of light suddenly and briefly emanating from the lunar surface.

Anthony Cook, an astronomical observer at Los Angeles’ Griffith Observatory which streamed the eclipse, thought it could have just been the camera’s random electronic noise. Then astronomers and citizen scientists started to share their detection of the flash on Reddit and Twitter.

The only explanation was that something slammed into the lunar surface and obliterated itself.

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The moon is a multi-billion-year-old library of impact events, with fresh collisions still taking place frequently today. Capturing a lunar impact on video is rare enough, but this event — a collision during a total lunar eclipse — may be a first.