New observations have dramatically reduced the chances of asteroid 2024 YR4 hitting Earth in 2032, lowering the risk to minimal levels, but its extraordinarily close approach will offer astronomers the chance to examine it in detail
By Alex Wilkins
21 February 2025
Astronomers have raced to observe asteroid 2024 YR4
NASA/Magdalena Ridge 2.4m telescope/New Mexico Institute of Technology/Ryan
The world’s space agencies have reduced the chances of asteroid 2024 YR4 impacting Earth to below 1 per cent, which strongly suggests that a potentially devastating collision will be avoided. However, the asteroid will still probably pass extraordinarily near to our planet, giving astronomers a rare opportunity to observe an asteroid up close.
“We are not expecting the impact probability to rise back above 1 per cent for the close approach with Earth in 2032,” says Richard Moissl at the European Space Agency (ESA). “The most likely further development is a further drop in the impact probability, likely even to 0.”
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Alarms about asteroid 2024 YR4 were first raised in December last year, when astronomers found it might be on a collision course for Earth in 2032. It appears to be between 40 and 90 metres wide and could generate a deadly blast should it hit a city. In the following weeks, the world’s telescopes and space agencies closely tracked its trajectory, honing its future path with greater precision. It reached its highest impact risk on 17 February, with a 1-in-32 chance, but in the days after, this fell to 1-in-67, or a 1.5 per cent risk.
On 20 February, new observations led to a sharp downgrade of this risk, with NASA putting it at a 0.27 per cent chance of impact, or 1-in-360, and ESA even lower, at 0.16 per cent, or 1-in-625. These ratings put it at a 1 on the 10-point Torino scale used to assess the hazard posed by such objects. That score is down from 3, meaning 2024 YR4 is now considered one of many low-risk asteroids that are discovered each year, but that ultimately miss Earth.
This is good news, says Gareth Collins at Imperial College London, but the asteroid will still be useful as a dry run for our planetary defence systems and for scientific purposes. “This is still something that will make a spectacularly close approach. If the risk of hitting was as high as it was, it must be coming very close to us,” he says.