'City-killer' asteroid has a 1-in-43 chance of smashing into Earth in 2032, NASA says

NASA scientists have just spotted a hunk of space rock that could smack into Earth in 2032. And while it's unlikely to wipe out humanity, it could take out a city.

The asteroid, dubbed 2024 YR4, was detected by NASA's Asteroid Terrestrial-impact Last Alert System on Dec. 27, 2024. According to the latest NASA estimates, it has about a 1-in-43 chance of impacting our planet in 2032.

But there's some good news for Earth: 2024 YR4 is only around 180 feet (55 meters) across, which means it is too small to end human civilization if it collided with Earth. But it could wipe out a major city. Scientists estimate that it would release about 8 megatons of energy upon impact — more than 500 times that of the atomic bomb that destroyed Hiroshima, Japan.

Although the asteroid is currently moving away from us, Earth will have several close shaves with the space rock in the next half century. Its next sideswipe will occur in late 2028, followed by six more close approaches between 2032 and 2074. Of these, the one with the highest chance of impact will be on Dec. 22, 2032, according to NASA. As the asteroid gets closer, scientists will have a much better sense of its trajectory and likelihood of hitting Earth.

All of these factors place 2024 YR4 at Level 3 on the Torino Impact Hazard Scale, the system scientists use to determine an asteroid's threat level. For objects at this level, "attention by public and by public officials is merited if the encounter is less than a decade away." However, most asteroids in this category are eventually downgraded to Level 0, which means "the likelihood of a collision is zero, or is so low as to be effectively zero."

Threats like this are the reason NASA and other space agencies are interested in developing techniques to redirect asteroids, as demonstrated by the Double Asteroid Redirection Test mission. The chances of a catastrophic asteroid impact are usually very low, so it is crucial to continue monitoring objects of interest, astronomers say. Even though 2024 YR4 probably won't trigger a mass extinction like the dino-killing space rock that slammed into what is now Mexico 66 million years ago, astronomers will keep a close eye on the asteroid as it circles back toward our planet.

Editor's note: This article was updated on Friday (Feb.7) after NASA increased the likelihood of a potential impact.