Newly discovered asteroid 2024 YR4 has a 2% chance of hitting Earth

Astronomers track asteroid 2024 YR4 to refine impact risk and trajectory.

Illustration by Jose A. Bernat Bacete

By Laila Azzahra and Hayu Andini

Astronomers have identified a newly discovered asteroid, named 2024 YR4, which currently has a 2% chance of impacting Earth in 2032. While the probability remains low, researchers are closely monitoring the space rock to better understand its trajectory and potential risks. The effort may soon involve the most advanced space observatory ever launched—the James Webb Space Telescope.

Little is known about 2024 YR4, but estimates suggest it is between 131 and 295 feet (40 to 90 meters) wide—comparable in size to a large building, according to Dr. Paul Chodas, manager of NASA’s Center for Near-Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory (JPL) in Pasadena, California.

How 2024 YR4 compares to past asteroid threats

While 2024 YR4 is much smaller than the asteroid that wiped out the dinosaurs 66 million years ago—estimated to be about 6.2 miles (10 kilometers) in diameter—its size is still large enough to cause significant regional damage if it were to impact Earth. Planet-killer asteroids, defined as those over 1 kilometer in diameter, pose catastrophic risks, but even smaller asteroids like 2024 YR4 can be destructive.

For example, the 1908 Tunguska event in Siberia was caused by an asteroid around 98 feet (30 meters) wide. The explosion leveled 830 square miles (2,150 square kilometers) of forest. Similarly, in 2013, a 66-foot-wide (20-meter-wide) asteroid exploded over Chelyabinsk, Russia, releasing energy 20 to 30 times greater than the Hiroshima atomic bomb, injuring over 1,000 people.

If 2024 YR4 is on the larger end of its estimated size range, an impact could produce blast damage extending up to 31 miles (50 kilometers) from the impact site, according to Chodas. However, the asteroid’s exact risk level remains uncertain, which is why scientists are working urgently to gather more data.

James Webb Space Telescope to study 2024 YR4

Scientists have a limited window to observe 2024 YR4 before it fades from view in April 2025. To refine its trajectory and determine its exact size, astronomers plan to use the James Webb Space Telescope, one of the most powerful observatories ever deployed.

Since its discovery on December 27, 2024, by the ATLAS telescope in Chile, 2024 YR4 has been tracked by multiple telescopes worldwide. However, ground-based observations rely on visible light reflected from the asteroid’s surface, which makes precise size measurements difficult. Webb, which detects infrared radiation, will instead measure the heat emitted by the asteroid, allowing for a much more accurate estimate of its size and composition.

The telescope is expected to begin observing 2024 YR4 in early March, with a follow-up campaign scheduled for May. These observations will help astronomers refine the asteroid’s orbit and determine if its path intersects with Earth’s in the future.

Tracking efforts and planetary defense

Observatories in New Mexico, Chile, and Hawaii are actively monitoring 2024 YR4. The Pan-STARRS telescope in Maui, one of the world’s leading near-Earth object detection systems, is playing a key role in tracking the asteroid’s movements.

"Hawaiʻi’s telescopes are some of the most important tools for planetary defense," said Doug Simons, director of the University of Hawaii’s Institute for Astronomy. "Thanks to our prime location and advanced technology, we can spot, track, and study asteroids with incredible accuracy."

Astronomers estimate that there are around 600,000 asteroids in the same size range as 2024 YR4, but only 12,000—about 2%—have been detected so far. This highlights the ongoing need for improved asteroid-tracking efforts.

What happens next?

If 2024 YR4 disappears from view before astronomers can confirm it will not impact Earth, it will remain on the risk list until it reappears in June 2028. Current orbital models suggest it will pass near Earth every four years, though it is not expected to pose a threat in 2028.

Scientists will continue gathering data to determine whether 2024 YR4’s path could lead to an impact in 2032. If new observations reduce the probability to zero, it will be removed from the watchlist. Otherwise, future missions may be necessary to study the asteroid further—or even to develop potential deflection strategies.

As asteroid detection technology advances, researchers hope to improve their ability to track and mitigate potential threats. For now, all eyes remain on 2024 YR4, as astronomers race against time to unlock its secrets before it vanishes from view.