The meteorite weighing almost half a tonne hit the lunar surface in September last year, in Mare Nubium, an ancient lava-filled basin with a darker appearance than its surroundings.
The impact produced an extraordinary flash which is the longest and brightest ever recorded on the Moon, the astronomers said.
The flash was briefly almost as bright as the familiar Pole Star, and anyone on Earth who was lucky enough to be looking at the Moon would have been able to see it.
The impact was produced by a car-sized meteorite with a width of between 0.6 and 1.4 metres, 'Sci-News.com' reported.
The rock hit Moon at about 61,000 km per hour and created a new crater with a diameter of around 40 metres.
The impact energy was equivalent to an explosion of about 15.6 tonnes of TNT.
Professor Jose Madiedo from the University of Sevilla and the University of Huelva in Spain developed a video of the impact, showing an afterglow of the flash that remained visible for a further eight seconds.
"At that moment I realised that I had seen a very rare and extraordinary event," Madiedo said.
The rocks become molten and are vaporised at the impact site instantaneously because such impacts take place at huge speeds.