A massive asteroid that sent shockwaves through the scientific community just weeks ago—after it was briefly deemed a potential threat to Earth—may now be on a collision course with the Moon. According to new data from top space agencies, asteroid 2024 YR4, which measures around 197 feet (60 meters) in length, no longer poses a risk to our planet. However, astronomers now estimate a 2% probability that it could strike the Moon.
The new findings, made possible by the James Webb Space Telescope (JWST) on March 26, provide a more precise analysis of the asteroid’s trajectory. Julia de León, a planetary scientist at the Institute of Astrophysics of the Canary Islands and a key figure in Europe’s planetary defense strategy, shared her excitement about the potential lunar impact.
“If it hits the Moon, it wouldn’t pose any danger to us—nothing would really happen. But it would be an incredible opportunity to observe a lunar impact and its immediate consequences,” de León explained to El País. “We know the Moon is covered in craters, and we know small objects hit its surface all the time, but we’ve never seen a collision of an object larger than 164 feet (50 meters). It would be amazing.”
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From global threat to scientific opportunity
Asteroid 2024 YR4 first made headlines in early February when NASA and the European Space Agency (ESA) confirmed that it could potentially collide with Earth, prompting the United Nation to activated the Planetary Security Protocol for the first time in history. The space rock, estimated at the time to be between 40 and 90 meters in size, was classified at Level 3 on the Torino Scale, indicating a 1% chance of impact.
Those calculations for impact rose to 3.1% according to NASA over the following days. However, after they were refined using various observatories, the risk probability was significantly lowered to nearly zero, eliminating concerns about a direct impact on our planet.
But while Earth is safe, the Moon may not be. The latest observations from JWST suggest that the asteroid’s actual size is around 60 meters, which is significant because it surpasses the 50-meter threshold that triggers an alert from the United Nations Space Mission Planning Advisory Group—a task force dedicated to devising strategies for deflecting potentially hazardous near-Earth objects.
“This is the size threshold where an asteroid could cause significant damage,” de León noted. “With a diameter of 60 meters, an impact could create destruction within a radius of 50 to 62 miles (80 to 100 kilometers).”
Remembering Chelyabinsk: The dangers of space rocks
Although an impact on the Moon would be harmless to Earth, planetary defense experts are closely watching 2024 YR4 because of the devastation asteroids of similar size have caused in the past. One of the most striking examples is the Chelyabinsk event of 2013, when a 66-foot (20-meter) asteroid entered Earth’s atmosphere over Russia. Despite its relatively small size, it exploded with the force of 35 Hiroshima-sized atomic bombs, shattering windows across thousands of buildings and injuring approximately 1,500 people due to the blast wave.
Image by Michael Carroll in 2013. We did NOT see the little one coming; it hit Earth above Chelyabinsk in 2013, injuring >1400 people. Asteroid 2024 YR4 is bigger than the little one & perhaps as large as the football field! JWST 🔭 data next month will help pin down the size. pic.twitter.com/dK5h1l32Wg
— Dr Heidi B. Hammel (@hbhammel) February 19, 2025
While the possibility of another Earth impact is off the table for now, scientists are eager to study what happens if 2024 YR4 collides with the Moon. “Honestly, I hope it does,” de León admitted. “We could track the impact using space and ground-based telescopes. It would be a truly fantastic learning opportunity.”
Researchers will continue monitoring the asteroid, with another round of James Webb observations scheduled for May to refine estimates of its lunar impact probability.
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