Of course, rocks and asteroids crash into the moon all the time (there's a reason it's so cratered.) But there's something about seeing it in action — and at this size — that's pretty amazing.
So how big was the crash? So big that researchers say the flash it created was very, very briefly was around the same brightness as the North Star (the brightest ever lunar impact flash observed) and that it resulted a crater 130 feet wide. You can read more about it in this paper from astronomers led by José Madiedo at the Universidad de Sevilla and Huelva for the Monthly Notice of the Royal Astronomical Society. Or just watch this video where they explain now: