Chance of a devastating asteroid impact briefly spiked in 2025

The chances of a devastating asteroid impact briefly increased in 2025 after astronomers discovered a building-sized asteroid hurtling toward Earth.

The asteroid, named 2024 YR4, was the first discovered by astronomers at the end of December 2024, its width was estimated to be between 40 and 90 meters. Its possible trajectories through our solar system passed through Earth's narrow window, and astronomers at the time calculated that it had a 1 in 83 chance of colliding with the planet in 2032.

By making more detailed observations of the asteroid's trajectory in the early months of 2025, astronomers calculated the increasingly likely chances of an impact, reaching the most dangerous probability level of 1 in 32 in early February.

If the hypothetical impact occurred near the city, the effects would be devastating, releasing the equivalent of megatons of TNT. The asteroid was considered dangerous enough that it was briefly given a score of 3 on the 10-point Turin impact rating system, where 0 means there will be no impact and 10 means it will cause a global catastrophe. It also prompted several United Nations-affiliated organizations to take further action, such as coordinating global telescope observation campaigns and holding meetings to decide whether an asteroid deflection mission might be needed.

During this time, the world's space agencies met regularly and coordinated their efforts to compare their observations and try to better understand the asteroid. “The 2024 YR4 has been a great teacher for us,” says Richard Moissl at the European Space Agency (ESA). “It was great training that improved our [asteroid detection] methods and our understanding of the whole issue.”

By February 20, astronomers had refined the orbit of 2024 YR4 enough to almost completely exclude Earth from the window through which the asteroid would have passed, and ESA quickly reduced the risk of impact to 1 in 625, or 0.16 percent. A few weeks later, NASA and ESA said there was no chance of a collision at all. “It’s not perceived as a threat to Earth,” Moissl says.

However, astronomers could not rule out a possible impact on the Moon: the current risk in 2032 would be about 4 percent. “If a lunar impact were to occur, it would be a great opportunity to learn about the impact process and witness it from some safe distance,” he says. Gareth Collins at Imperial College London.

Scientists have begun to calculate the possible consequences of a collision with the Moon, for example, an asteroid that released a shower shrapnel destroying satellites to Earth, and whether a deflection mission is possible and what strategy might be most effective: from launching small satellites at an asteroid to blow it up with a nuclear bomb. “You have to do this very, very carefully so you don't turn a lunar impact into an Earth impact,” Moissl says.

Our imprecise figure of a 4 percent chance of impacting the Moon is currently not high enough to cause the world's space agencies to seriously plan the mission. This figure is also unlikely to change anytime soon, as 2024 YR4 is currently behind the Sun and therefore not visible to telescopes – and it won't appear again until 2028. However, we will have one rare chance to see it in February 2026 using the James Webb Space Telescope due to its unique vantage point in orbit around Earth. Data from these observations will be our last real chance to decide whether we want to launch some kind of mission to visit or deflect the asteroid, Moissl says, since developing a mission to an asteroid could take many years.

2027 Total Solar Eclipse Cruise: Spain and Morocco

Embark on an extraordinary voyage aboard the state-of-the-art expedition ship Douglas Mawson to witness the longest total solar eclipse remaining this century, on August 2, 2027.