The risk of an asteroid impact on Earth has doubled within a week, with experts now estimating a 2.3% chance that asteroid 2024 YR4 could collide with the planet on December 22, 2032. The asteroid, approximately 90 meters wide, was first detected two days after it passed by Earth on Christmas Day 2024, using a telescope in Chile. Currently, it sits at the top of NASA and the European Space Agency’s (ESA) risk registers, prompting heightened monitoring from the global scientific community.
If the asteroid were to impact Earth, it could cause localized devastation, similar to the Tunguska event in 1908, when an asteroid of comparable size flattened 1,000 square miles of forest in Siberia. Scientists estimate that 2024 YR4, which weighs almost a quarter of a million tonnes, would explode with the force of 2.2 million tonnes of TNT, equivalent to 150 times the Hiroshima atomic bomb. While the UK and North America are not within the expected impact zone, some of the at-risk areas include Lagos, Accra, Mumbai, Venezuela, and Colombia.
Observations of the asteroid will continue until early May when it will disappear from view until 2028—just four years before its projected close approach. While astronomers work to refine calculations, officials note that a risk level above 1% for an asteroid over 50 meters wide is typically enough to trigger global discussions on potential deflection missions. The James Webb Space Telescope (JWST) is expected to play a role in analyzing the asteroid’s composition, size, and velocity to aid decision-making.
If the risk level continues to rise, space agencies may consider launching a dedicated space telescope for closer monitoring or even start developing a mission to deflect the asteroid using a spacecraft impactor, similar to NASA’s successful DART mission in 2022. A meeting of the ESA-led Space Mission Planning Advisory Group (SMPAG) was recently held in Vienna, with plans to advise the United Nations on possible next steps.
Despite the current 2.3% risk, experts remain cautious, emphasizing that further calculations are likely to adjust the probability. The most probable outcome, they say, is that the risk will eventually diminish to zero. However, as the asteroid remains under surveillance, decisions regarding planetary defense missions could be made by the summer of 2025 if necessary.
