Rock travelling at 61,000 km/h punched a crater 40 metres wide and produced a flash that could be seen from Earth
Astronomers have captured the moment a lump of rock slammed into the moon with so much force that the bright flash could be seen from Earth with the naked eye.
The 400kg (63st) meteorite, travelling at 61,000 km/h (40,000 mph), punched a fresh crater on the moon's surface some 40 metres wide in what is thought to be the largest lunar impact ever recorded.
The rock, which was about a metre in diameter, ploughed into an ancient lava-filled basin called the Mare Nubium, producing a flash almost as intense as the Pole Star that took more than eight seconds to fade.
The impact energy was equivalent to 15 tonnes of TNT – at least three times as great as that from the previous record-holding lunar impact, observed by Nasa in March last year.
The flash was picked up by two telescopes in Spain's Midas observatory. Photograph: J Madiedo/Midas
The event was recorded by Spanish telescopes that monitor the moon under a project called Midas (Moon Impacts Detection and Analysis System). The flash was picked up at 8.07pm GMT by two telescopes in Seville, southern Spain. Both were peering at the unlit side of the moon where the bright flickers from impacts are easier to spot.
Unlike Earth, the moon has no atmosphere to protect it from incoming meteorites, so the surface is pocked with craters. The rock would have swiftly burned up in the Earth's atmosphere long before it reached the ground.
Details are published in the latest Monthly Notices of the Royal Astronomical Society.
Astronomer Jose Madiedo, who leads the Midas project at the University of Huelva, saw footage of the strike soon after the telescopes' software had processed the impact on 11 September 2013. "When I saw it on the screen I realised I had witnessed a rare and unusual event. It was really huge. I couldn't imagine such a bright event," he said. "We image a lot of impacts on the moon, but they're caused by very small rocks. They can be the size of a nut, and just a few grammes, and go up to 1kg. But this event was really impressive and very rare," he said.
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