Asteroid Once Feared to Hit Earth Now Poses Risk to Moon, Scientists Say

Asteroid 2024 YR4, a 60-meter-wide object discovered in late 2024, has shifted from being the greatest known impact risk to Earth to a new potential threat to the moon, according to recent astronomical observations. Initially, the asteroid was given a 3.1% chance of hitting Earth by February 2025—the highest ever recorded for such an object—but improved tracking ruled out any danger to the planet by June 2025.

NASA data now indicate a 4.3% probability that 2024 YR4 could collide with the lunar surface in late 2032. While the likelihood remains low, scientists are assessing possible consequences for both lunar infrastructure and satellites in Earth's orbit. Should the asteroid strike the moon, experts estimate it would create a crater about one kilometer wide and release roughly 100 million kilograms of debris. Some of this material could reach Earth, producing a meteor shower visible to the naked eye, but not posing a threat to people on the ground. However, Dr. Paul Wiegert of Western University in Ontario warned that even small debris particles could damage satellites, potentially exposing them to a decade's worth of debris in just a few days.

The potential lunar impact has also raised concerns for future lunar bases and equipment, as the moon's lack of atmosphere offers no protection from high-velocity fragments. Dr. Wiegert noted, "We now have things worth protecting that are a bit further away from Earth," highlighting a shift in planetary defense priorities. While missions like NASA's DART have demonstrated asteroid deflection for Earth, experts say a similar strategy to protect the moon would require further study closer to 2028, when YR4 becomes observable again.

Asteroid 2024 YR4 was detected only after passing near Earth, as its approach was concealed by the sun's glare. This incident has underscored the need for improved detection systems. Upcoming missions, including NASA's NEO Surveyor and the European Space Agency's NEOMIR, aim to address current observational blind spots. ESA's Richard Moissl stated that NEOMIR would have detected YR4 a month earlier than existing telescopes. The Vera C. Rubin Observatory in Chile and the James Webb Space Telescope have also contributed to tracking and characterizing YR4, confirming its size and eliminating Earth as a target.