The new observations of asteroid 2024 YR4 confirm it. The probability that clash against the earth in 2032 are one between a thousand. But now they raise the risk of impact on the moon to 4 percent. The asteroid that can hit the moon still threatens us. What could happen in case of collision with the ejection of lunar material to space? It would threaten infrastructure and spatial operations in the Earth-Line system.
Asteroid 2024 YR4 was discovered in December 2024. It generated the first notification of the international asteroid alert network (IAWN) on January 29, 2025. The first calculations predicted a 1.3 % impact probability with the Earth on December 22, 2032. They estimated their size between 40 and 90 meters.
Follow-up
These estimates gave the asteroid a 3 risk rating on the Turin scale, with a range of 0 to 10. This makes it an objective that deserves the attention of astronomers. The observations have been published in Research Notes of the AAS.
The world astronomical community quickly launched an international observation campaign. The researchers at the University of Helsinki are at the forefront. They use the Nordic Optical Telescope (Not) of 2.5 meters on the Canary Island of La Palma. The asteroid that can hit the moon is subject to permanent control. «We have focused on the precise position and movement of the asteroid. It is crucial to better predict their future career, ”they say in a statement.
It is true that the risk of impacting the earth descended. But now there is a 4 % probability that the asteroid impact the moon. «If it happens, the Earth-Luna system could be cloudy by particles detached from the moon and the asteroid. Threat infrastructure and human spatial operations, ”they explain.
Dangerous diameter
The James Webb space telescope observed the asteroid on March 26. The initial estimation of the asteroid diameter was limited to measurements in visible light, which depend both on the size and surface reflectivity. After working hours, the team reached an estimate: there is a 95 % probability that the diameter is between 46 and 74 meters.
This size determination will help astronomers evaluate the possible consequences of an impact with the moon. Despite the reduction of risk, terrestrial and spatial observatories will continue to track YR4 until April or May 2025. From this, it will cease to be observable from Earth to its next approach in 2028.
