Asteroid 2024 YR4 is on a potential crash course with Earth, but there鈥檚 a very slight chance the moon could take the hit.
Based on current observations, there is a 2.1 per cent chance that the asteroid 鈥� about as long as the Leaning Tower of Pisa is tall 鈥� will crash into our planet on 22 December 2032. Although it is very likely to miss, a direct strike on a populated area would be catastrophic. But if it is in fact heading directly our way, new calculations show that there is a very small chance 鈥� about 0.3 per cent 鈥� that this stony missile will impact the moon instead.
That the moon could feasibly take the hit for all 8 billion of us would be quite the cosmic plot twist. But it鈥檚 within the realm of possibility, according to by at the University of Arizona, a member of the asteroid-hunting Catalina Sky Survey.
Advertisement
A lunar impact would be preferable to an Earth impact. The moon might be left with a fresh crater anywhere from about 500 to 2000 metres across, but humanity would be unharmed. 鈥淭here is the possibility this would eject some material back out that could hit the Earth, but I highly doubt it would cause any major threat,鈥� says Rankin.
at Imperial College London agrees. 鈥淲e would be quite safe on Earth,鈥� he says. 鈥淪ome small ejecta fragments might reach Earth, but [would be] totally harmless鈥� and would burn up in the atmosphere.
Unlike Earth, the moon lacks an atmosphere to slow 2024 YR4 down. Instead, the asteroid would plunge unimpeded into the silvery surface at a staggering 50,000 kilometres per hour, creating an explosion 343 times more powerful than the atomic bomb dropped on Hiroshima.
The orbit of 2024 YR4 still has considerably uncertainty. Planetary defence astronomers are basing their forecasts on hundreds of observations taken of the asteroid since late December, and while most projections show it missing Earth in 2032, a handful of them terminate in an Earth impact. As more observations come in, those odds can rise and fall.
The moon also falls within that range of uncertainty, and Rankin鈥檚 calculations 鈥� corroborated by those of his colleagues 鈥� show that the moon has a slim chance at becoming 2024 YR4鈥檚 final destination. Should it hit the moon, the area of possible impact sites stretches from just south of Mare Crisium, a frozen sea of lava, to Tycho, an ancient impact crater 鈥� all on the side of the moon facing Earth.
The explosion 鈥渨ould be very obvious to any spacecraft observing from lunar orbit鈥�, says at the SETI Institute in California. But it may not be for the unaided eye from Earth, as 鈥渢he flash would be competing with the brightness of the rest of the moon鈥�.
Others are more optimistic that we will get a spectacular fireworks show. 鈥淭he impact flash of vaporised rock would be visible from Earth, even in the daytime,鈥� says Collins.
And Rankin reports that his colleague, astronomer at Northolt Branch Observatories in London said, 鈥淭he impact could be brighter than the full moon. Safe to say it would be visible with the unaided eye.鈥�
