Kring and his colleagues used photogeologic mapping of the canyons, Vallis Schrödinger and Vallis Planck, to reconstruct their catastrophic backstory. The team’s models suggest that they were forged by rays of rocky ejecta traveling at about 2,800 miles per hour, which violently tore gashes into the lunar landscape within ten minutes of impact. Ten minutes! Imagine blasting out two Grand Canyons in the time it takes to boil an egg. You have to hand it to space rocks: They know how to make a lasting impression.