According to a NASA statement
Luckily, though, JWST also confirmed what NASA has known for weeks: 2024 YR4 is no longer a hazard collision with the moon
“While an Earth impact by 2024 YR4 on December 22, 2032 has now been ruled out, it continues to have a non-zero probability of impacting the Moon at this time,” the researchers wrote in their preliminary report solar system for the next several years.
Related: NASA’s most wanted: The 5 most dangerous asteroids to Earth
Tracking a “city-killer”
Astronomers first discovered asteroid 2024 YR4 in December 2024. Initial observations with ground-based telescopes indicated that the space rock had a diameter of about 180 feet (55 meters) — roughly as wide as the Leaning Tower of Pisa is tall.
Its orbital trajectory frequently crosses Earth’s route around the sun, making a direct collision with our planet possible. If such a strike were to occur, it could wipe out an entire city with the equivalent force of 500 Hiroshima bombs
A NASA graphic of the possible locations (yellow points) of asteroid 2024 YR4 on Dec. 22, 2032, as of Apr. 2, 2025. (Image credit: NASA JPL/CNEOS)
While analyzing the asteroid’s trajectory, researchers briefly estimated that 2024 YR4 had up to a 3.1% chance of crashing into Earth European Space Agency (ESA) announced
Key to these observations are JWST’s infrared
“In general, the brighter the asteroid, the larger it is, but this relationship strongly depends on how reflective the asteroid’s surface is,” ESA officials wrote in a Feb. 10 blog post
JWST made its first observations of the asteroid on March 26, watching the asteroid rotate once every 20 minutes over a five-hour period. The researchers then converted the asteroid’s brightness to mid-infrared wavelengths, taking into account the known distances and angles between the asteroid, the sun and JWST.
With these data, the team estimated that asteroid 2024 YR4 is slightly larger than was previously estimated, measuring about 200 feet (60 m) in diameter (this is roughly in the middle of NASA’s estimated size range of 174-220 feet wide). The thermal analysis also suggests that the asteroid is cooler than is typical for objects of this size, hinting that it may be rockier than previously thought as well.
Front-row seats to a lunar impact?
But even if 2024 YR4 is a bit bigger and harder than we thought, it still poses no imminent threat to Earth, the JWST data confirm. But there does remain a roughly 3.8% chance that the asteroid will slam into the moon in 2032, according to NASA.
While a lunar impact may sound scary, the moon endures thousands of tiny meteor strikes
“We’ve got our fingers crossed for a moon impact,” Alan Fitzsimmons New Scientist
The second round of JWST observations, scheduled for May, will further help to refine the asteroid’s orbital trajectory and its chances of hitting the moon.
Editor’s note: This article was updated on April 3 with new facts and figures from NASA.
