NASA’s Center for Near-Earth Object Studies estimated on February 6, 2025, that asteroid 2024 YR4 had a 2.3% chance of hitting Earth on December 22, 2032. The calculation was equivalent to odds of roughly one in 43, up from the European Space Agency’s estimate of 1.3% about a week earlier.
The object had been detected by a NASA-funded telescope in Chile shortly before the end of 2024. Early observations indicated a possible width of as much as 90 metres. That placed it in a size range comparable to the object associated with the 1908 Tunguska explosion, which flattened about 2,150 square kilometres of remote Siberian forest. The comparison concerned scale, not a prediction of identical consequences.
2024 YR4 rose to the top of official impact-risk lists and received level three on the Torino scale, which runs from zero for no risk to 10 for a civilisation-ending collision. A level-three rating calls for attention from astronomers; it does not mean impact is the likely outcome. Even at 2.3%, the calculation implied a 97.7% chance that the asteroid would miss Earth.
Scientists said changing probabilities were normal when an object had been observed over only a short arc of its orbit. Additional measurements refine estimates of speed and trajectory. As the projected path narrows, Earth can initially remain within the range of possible positions, causing the numerical risk to rise, before later data remove the planet from that corridor.
NASA researcher Molly Wasser noted that previous objects had climbed risk lists and then fallen away as observations accumulated. Colin Snodgrass, a professor of planetary astronomy at the University of Edinburgh, likewise said the asteroid would most likely pass harmlessly but deserved continued telescope attention until its orbit could be confirmed more precisely.
Past experience supported that caution. Asteroid Apophis once reached Torino level four after its 2004 discovery, but later calculations ruled out a threat during its close approaches for at least a century. Such examples do not determine 2024 YR4’s path; they show why a preliminary percentage should not be treated as a fixed forecast.
Researchers also had evidence that asteroid deflection was technically possible if ever required. NASA’s 2022 DART mission deliberately struck an asteroid and changed its trajectory. Snodgrass said an object on 2024 YR4’s scale could be suitable for a similar approach. On February 6, however, the immediate task was observation, not intervention: the reported risk remained low, uncertain and expected to change with better data.
