The moon will officially be spared an explosive encounter with a ‘city-killer’ asteroid in 2032, new observations from The James Webb Space Telescope (JWST) reveal.
Collected on February 18 and February 26 with JWST’s sensitive infrared instruments, the new near-Earth observations asteroid 2024 YR4 allowed NASA astronomers to refine previous estimates of the rover’s trajectory – reducing the chances of a lunar impact from 4.3% to zero.
The riskiest asteroid ever
Asteroid 2024 YR4 was discovered in late 2024 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) network
Subsequent telescope observations soon showed that the rover was a crunch, measuring between 174 and 220 feet (53 to 67 meters) in diameter—about as wide as the Leaning Tower of Pisa is tall—and that its orbit would bring it extremely close to Earth. If an asteroid of this size were to hit our planet, it could wipe out a city with the equivalent force of 500 Hiroshima bombs, Live Science previously reportedand gives it the nickname “city killer”.
While telescope data on the asteroid was still limited, astronomers estimated that it had a small chance of smashing into Earth. The predicted probability of a collision peaked at 3.1%, which was the highest chance of a potential asteroid collision ever. Within months, new data from JWST and other telescopes brought those odds down to zero, while the chances of a lunar collision remained at 4.3%.
What would happen if such a large asteroid hit the moon? It certainly wouldn’t be the first time the moon had been hit by a space rock, but it would be the first time scientists could predict a large lunar impact from a known asteroid and watch it happen in real time. Some astronomers theorized that the resulting explosion could have been visible from the ground with the naked eyewhile others warned of a potential rain of debris that could trigger a brand new meteor shower over our planet.
Now, with the Earth and Moon officially confirmed as of 2024 YR4, the asteroid will remain a tempting target for astronomers looking to test planetary defense modelsand it can help us prepare for more close meetings. NASA plans to see the asteroid with JWST again in 2028, when it heads back our way — and passes safely.
