On 11 September 2013, did you see anything odd on the face of the Moon?

If you were looking up at 20:07 UTC, you would have witnessed something historic — a bright flash of light lasting for about eight seconds, the result of the largest meteorite that we’ve ever seen crashing into our natural satellite.

The 400kg meteorite, which measured about a metre across, was detected by Spain’s Moon Impacts Detection and Analysis System when it slammed into the lunar surface at 61,000 kilometres per hour. It created an explosion equivalent to 15 tonnes of TNT — three times stronger than the last notable lunar impact in March 2013.

“Usually lunar impacts have a very short duration — just a fraction of a second. But the impact we detected lasted over eight seconds. It was almost as bright as the Pole Star, which makes it the brightest impact event that we have recorded from Earth,” said Jose Madiedo, who reported the event in the Monthly Notices of the Royal Astronomical Society. He added: “This is the largest, brightest impact we have ever observed on the Moon.”

However, don’t be too alarmed. If a rock of that size hit Earth it would burn up in our atmosphere as a shooting star before reaching the ground. Meteorites must be quite a bit larger to reach the surface, like the 19-metre rock that exploded over Chelyabinsk in Russia in February 2013.

It’s thought it will have left behind a forty-metre wide crater, but that’s just an estimation based on impact models. Once Nasa’s Lunar Reconnaissance Orbiter makes it way over the site, we’ll know for sure

Those with a distaste for text probably won’t have got this far, but just in case, here’s a video about the whole thing.