For the first time, astronomers and eclipse-watchers around the globe caught sight of a piece of space debris - most likely a meteoroid - slamming into the surface of the Moon as it passed through the shadow of Earth.
Such a scene has been long-sought by astronomers, but proved elusive until now, even with the frequency of lunar eclipses. Although meteoroids have been filmed hitting the Moon before, lunar eclipses are often too bright.
He doubled the number of telescopes the program usually has pointed at the Moon - from four to eight - and crossed his fingers.
"I had a feeling, this time will be the time it will happen," he told New Scientist. "I was really, really happy when this happened."
He caught the entire thing on film, but he didn't end up being the first to declare it.
Perhaps because the impact occurred in a darker region of the lunar surface, the bright flash was caught by other observers too, and speculatively posted to Reddit before Madiedo's confirmation came on Monday.
In a video from Griffith Observatory, the slam, visible as a brief, bright flash, occurs on the lower left part of the Moon while the scientists discuss the Moon's colour.
Although the impact produced quite a bright flash, the rock itself was probably not very large. According to Madiedo's preliminary estimates, it was probably only around 2 kilograms (4.4 pounds) in mass, and about the size of a football.
It just goes to show that you're never too small to make an impact.