This rock, recorded on Sept. 11, 2013, carved out a new crater measuring 40 metres in width. It had the mass of a small car, weighed about 400 kilograms and was travelling at 61,000 km/h, according to an astronomer who described the event in the latest Monthly Notices of the Royal Astronomical Society.
Jose Madiedo, who leads the Midas (Moon Impacts Detection and Analysis System) project at the University of Huelva in Spain, was operating two telescopes when he spotted the telltale flash.
He says the crash was briefly almost as bright as the familiar Pole Star, meaning that anyone on Earth who was lucky enough to be looking at the moon at that moment would have been able to see it.
In the video recording made by Madiedo, an afterglow remained visible for a further eight seconds.
The event is being described as the longest and brightest confirmed impact flash ever observed on the moon.
“At that moment I realized that I had seen a very rare and extraordinary event,” Madiedo said.
The moon lacks the atmosphere that prevents small rocks from space from reaching its surface. Had the same rock approached the Earth, it would have burned up before reaching the ground.
Still, the Midas team plans to continue tracking these kinds of events to gain insight into the risk of similar but larger objects hitting the Earth.