NASA has said the chances have increased that a huge asteroid about the size of a 10-story building will smash into Earth's Moon.
Near-Earth asteroid 2024 YR4 was discovered in December 2024, and back then observations of its orbit revealed there was a chance it could hit Earth in 2032.
While the chances of impact initially rose from 1.2% to 2.3%, then to 2.6%, peaking at 3.1% on 18 February 2025, that risk then fell to practically 0% by the end of February.
However, in order to better calculate the risk that the asteroid poses to Earth, NASA pointed the James Webb Space Telescope at YR4 and found there's a chance it could hit Earth's Moon instead.
Will asteroid YR4 hit the Moon?
One of the key pieces of data retrieved by Webb has been a reduction in the known size of the asteroid, from a previous estimate of 131-295 feet (40-90 metres) to 174-220 feet (53-67 metres).
That's about the size of a 10-storey building.
But while the chance of YR4 hitting Earth has effectively been ruled out, what about the chance of it hitting our Moon?
Planetary defence experts at NASA’s Center for Near Earth Object Studies at the Jet Propulsion Laboratory have updated 2024 YR4’s chance of hitting the Moon on 22 December 2032 from 1.7% as of late February 2025, to 3.8% as of early April 2025.
This is based on data from the James Webb Space Telescope, as well as ground-based telescopes.
Of course, the key headline here is that there is a 96.2% chance the asteroid will miss the Moon.
Plus, as is often the case with potentially dangerous asteroids – and as we saw in the case of asteroid YR4's chances of hitting Earth – the probability of impact often rises before falling.
And even if the asteroid did hit the Moon, NASA says it would not change the Moon’s orbit.
Soon, asteroid 2024 YR4 will be too far away to be observed by ground-based telescopes.
It's continuing its orbital journey around the Sun, and will return to approach Earth in 2023.
Webb still has eyes on asteroid 2024 YR4 and will be able to observe it again in late April or early May 2025, when it should be able to help scientists firm up the probability it will hit Earth's Moon.
