Key points from article :
A newly observed asteroid named 2024 YR4, roughly the size of a city building, is no longer expected to collide with Earth—but it may instead strike the Moon in December 2032, according to a new study involving astronomers from the University of Western Ontario. Though not yet peer-reviewed, the study estimates a 4% chance of lunar impact, which could unleash the explosive energy of 6.5 megatons of TNT, forming a crater nearly 1 km wide.
While Earth may be spared a direct hit, the concern now shifts to space infrastructure. Researchers predict the collision would eject over 100 million kg of lunar debris, some of which may reach low Earth orbit (LEO) within days, posing a significant threat to satellites and possibly astronauts. Around 10% of this debris cloud could eventually accrete toward Earth, with millimeter-sized fragments presenting the most danger to spacecraft.
Using computer models, scientists simulated 10,000 possible asteroid paths, with 410 resulting in a Moon strike—most likely in the southern lunar hemisphere. The greatest risk arises if the asteroid hits the Moon’s trailing edge, as this would maximize debris velocity toward Earth. By 2032, the sheer number of satellites in orbit could mean hundreds to thousands of debris impacts, amplifying the threat.
The authors call for planetary defence efforts to include lunar protection, given the Moon’s potential role in cascading space hazards. As the satellite population continues to grow, safeguarding both Earth and its natural satellite could become a critical priority in the decades ahead.
