Author: Molly L Wasser

NASA has significantly lowered the risk of near-Earth asteroid 2024 YR4 as an impact threat to Earth for the foreseeable future. When first discovered, asteroid 2024 YR4 had a very small, but notable chance of impacting our planet in 2032. As observations of the asteroid continued to be submitted to the Minor Planet Center, experts at NASA Jet Propulsion Laboratory’s (JPL’s) Center for Near-Earth Object Studies were able to calculate more precise models of the asteroid’s trajectory and now have updated its impact probability on Dec. 22, 2032 to only 0.004% and found there is no significant potential for this asteroid to impact our planet for the next century. The latest observations have further reduced the uncertainty of its future trajectory, and the range of possible locations the asteroid could be on Dec. 22, 2032, has moved farther away from the Earth.

There still remains a very small chance for asteroid 2024 YR4 to impact the Moon on Dec. 22, 2032. That probability is currently 1.7%. 

NASA will continue to observe asteroid 2024 YR4 with observatories funded by its Planetary Defense Coordination Office, and NASA’s James Webb Space Telescope will observe the asteroid in March to further gain insights about its size for scientific purposes. 

While this asteroid no longer poses a significant impact hazard to Earth, 2024 YR4 provided an invaluable opportunity for experts at NASA and its partner institutions to test planetary defense science and notification processes. The latest data on all known near-Earth asteroids that could pose an impact hazard to Earth will continue to be available at NASA’s automated Sentry page. 

Observations made overnight on Feb. 19 – 20 of asteroid 2024 YR4 have further decreased its chance of Earth impact on Dec. 22, 2032, to 0.28%. NASA’s planetary defense teams will continue to monitor the asteroid to improve our predictions of the asteroid’s trajectory. With this new data, the chance of an impact with the Moon increased slightly to 1%. The latest data will continue to be available at NASA JPL’s automated Sentry page.

Now that skies are darker after a week of limited visibility around full moon, astronomers have resumed observations of asteroid 2024 YR4. Ground-based telescopes require dark skies to observe asteroids, which are often very faint. Around the time of a full moon, the sky becomes too bright to detect these faint points of light.

NASA’s Center for Near-Earth Object Studies at the agency’s Jet Propulsion Laboratory in Southern California has incorporated the new observations reported to the Minor Planet Center and on Feb. 18, updated the impact probability of asteroid 2024 YR4 in 2032 to 3.1%. This is the highest impact probability NASA has ever recorded for an object of this size or larger. However, on Wednesday, Feb. 19, new data collected overnight reduced the impact probability to 1.5%.

Each additional night of observations improves our understanding of where the asteroid could be on Dec. 22, 2032 and underlines the importance of gathering enough data so that our planetary defense experts can determine future risk to the Earth. NASA expects the impact probability to continue to evolve as new observations of asteroid 2024 YR4 are made over the coming days and weeks.

These recent observations have further constrained the uncertainty around the asteroid’s trajectory, and the yellow dots in the above graphics represent possible locations of the asteroid on Dec. 22, 2032. As we continue to observe the asteroid’s motion over time, the region of possible locations will shrink even further. For the impact probability to drop to zero, the Earth would need to fall outside of the range of potential locations of asteroid 2024 YR4 on Dec. 22, 2032.

Additionally, there is also a – much lower — chance this asteroid could impact the Moon. Current calculations estimate this impact probability to be 0.8%.

NASA’s Near-Earth Object Surveyor mission, set to launch no earlier than Sept. 2027, will accelerate NASA’s ability to discover unknown asteroids by hunting for them in the infrared. While dark in visible light, asteroids and comets glow in the infrared as they’re heated by sunlight. In addition, NEO Surveyor will add an in-space vantage point that complements ground-based observatories.

While still an extremely low possibility, additional observations and analysis of asteroid 2024 YR4 indicate that its impact probability with Earth has increased to a 2.3% chance on Dec. 22, 2032. Ongoing observations from ground-based telescopes involved with the International Asteroid Warning Network will continue while the asteroid is still visible through April, after which it will be too faint to observe until around June 2028.

NASA’s James Webb Space Telescope will also observe the asteroid in March 2025 to better assess the asteroid’s size. Currently the asteroid is estimated to be 130-300 feet across.

As more observations of the asteroid’s orbit are obtained, its impact probability will become better known. It is possible that asteroid 2024 YR4 will be ruled out as an impact hazard, as has happened with many other objects that have previously appeared on NASA’s asteroid risk list, maintained by NASA’s Center for Near-Earth Object Studies. It is also possible its impact probability will continue to rise. The latest data will continue to be made available via NASA’s automated Sentry page.

NASA analysis of a near-Earth asteroid, designated 2024 YR4, indicates it has a more than 1% chance of impacting Earth on Dec. 22, 2032 – which also means there is about a 99% chance this asteroid will not impact. Such initial analysis will change over time as more observations are gathered.  

 Currently, no other known large asteroids have an impact probability above 1%. 

 Asteroid 2024 YR4 was first reported on Dec. 27, 2024, to the Minor Planet Center– the international clearing house for small-body positional measurements – by the NASA-funded Asteroid Terrestrial-impact Last Alert System station in Chile. The asteroid, which is estimated to be about 130 to 300 feet wide, caught astronomers’ attention when it rose on the NASA automated Sentry risk list on Dec. 31, 2024. The Sentry list includes any known near-Earth asteroids that have a non-zero probability of impacting Earth in the future.  

There have been several objects in the past that have risen on the risk list and eventually dropped off as more data have come in. New observations may result in reassignment of this asteroid to 0 as more data come in. 

More information about asteroids, near-Earth objects, and planetary defense at NASA can be found at: 

https://nasa.gov/planetarydefense