NASA says asteroid 2024 YR4 will not hit the moon after all
Watch Andrew Rivkin, an astronomer who works in planetary defense, and EarthSky’s Deborah Byrd as they discuss asteroid 2024 YR4. For more than a year, scientists thought the asteroid could potentially strike the moon.
NASA says asteroid 2024 YR4 will not hit the moon
When asteroid 2024 YR4 was first discovered in December 2024, there were only a few observations to draw from. Because scientists didn’t have a long history of where it came from and the course it was taking, they didn’t know precisely where it would go in the future. This window of uncertainty included the possibility that the asteroid could strike Earth. That possibility was ruled out within a short period of time, but the possibility that it could hit the moon – while still unlikely – remained. But on March 5, 2026, NASA said it has ruled out the possibility of a lunar impact.
NASA said:
Using data from NASA’s James Webb Space Telescope observations collected on February 18 and 26, 2026, experts from NASA’s Center for Near-Earth Object Studies at the agency’s Jet Propulsion Laboratory in Southern California have refined near-Earth asteroid 2024 YR4’s orbit and are ruling out a chance of lunar impact on December 22, 2032. With the new data, 2024 YR4 is expected to pass by the lunar surface at a distance of 13,200 miles (21,200 km).
This update reflects improved precision in our understanding of where the asteroid is expected to be in 2032 rather than a shift in its orbital path. Previous analyses, made before the incorporation of these new observations, suggested 2024 YR4 had a 4.3% chance of lunar impact on this date.
The asteroid became unobservable in the spring of 2025, but now Webb has managed to get new observations. And those observations have allowed scientists to safely rule out a lunar impact in 2032.
At first we thought it might hit Earth
Asteroid 2024 YR4 first swept into the view of the ATLAS asteroid impact early warning system – with telescopes in Hawaii, Chile and South Africa – on December 25, 2024. And astronomers thought it might have a chance of hitting Earth.
It reached a 3 on the Torino Asteroid Hazard Scale, something no other asteroid has done, other than the infamous asteroid 99942 Apophis, which caused a stir when it achieved a Torino Scale rating of 4 in 2004.
As with Apophis, there was initially a lot of buzz about 2024 YR4. Check out this EarthSky interview with astronomer Richard Binzel of MIT, inventor of the Torino Scale.
But in February 2025, we learned that 2024 YR4 will not strike Earth in 2032. As a result, its rating on the Torino Scale dropped to near zero. Then, a new story emerged: Will 2024 YR4 strike the moon on December 22, 2032?
Possibilities of the asteroid striking the moon
The initial odds of the asteroid striking the moon, in February of 2025, were 1.8%, or a 1-in-56 chance.
Next, on April 2, 2025, NASA said that new data from the Webb space telescope and ground-based telescopes suggested a 3.8% chance of a moon strike.
Then, on June 3, 2025, the Webb achieved one more observation of the asteroid as it moved in its orbit around the sun. This observation helped to refine the space rock’s orbit. Astronomers updated their estimate of its chances of hitting the moon on December 22, 2032, from 3.8% to 4.3%. NASA went so far as to reassure the public that:
In the small chance that the asteroid were to impact, it would not alter the moon’s orbit.
But now, on March 5, 2026, NASA says the asteroid will not strike the moon in 2032.
How big is asteroid 2024 YR4?
Webb observations have helped astronomers refine their knowledge of this asteroid’s size. NASA said 2024 YR4 is somewhere between 174 to 220 feet (53 to 67 meters) in diameter, or about the size of a 15-story building. Previous estimates of the asteroid placed it at around 150 feet (46 meters). So it’s slightly bigger than we thought. An object that size striking Earth could take out a city.
The asteroid’s shape and origin
On April 8, 2025, NOIRlab said that observations with the Gemini South telescope reveal the asteroid’s shape and origin. Scientists said it has a bit of a hockey-puck-like shape. And they said it mostly likely came from the main asteroid belt. Both of these were unusual findings. Regarding the shape, team member Bryce Bolin of Eureka Scientific said:
This find was rather unexpected since most asteroids are thought to be shaped like potatoes or toy tops rather than flat disks.
And about the asteroid’s origin, Bolin said:
We are a bit surprised about its origin in the central main asteroid belt, which is a location in the asteroid belt that we did not think many Earth-crossing asteroids could originate from.
When the odds of 2024 YR4 hitting Earth plummeted
Inventor of the Torino scale Richard Binzel told EarthSky on February 23, 2025:
Asteroid 2024 YR4 has now been reassigned to Torino Scale Level 0: the level for No Hazard. Additional tracking of its orbital path reduces its possibility of intersecting the Earth to below the 1-in-1,000 threshold. That is the established level for downgrading to Level 0. [Editor’s note: Odds of 1-in-1,000 are the threshold for Level 0 for any space object smaller than 100 meters. The initial estimates of 2024 YR4 were for a size of 50 meters].
2024 YR4 fell to Torino Scale Level 1 (Green ‘Normal’) on February 20, down from Level 3 (Yellow ‘Meriting Attention by Astronomers’).
Level 0 is labeled as the (White) No Hazard zone on the Torino Scale, which considers the two dimensions of impact probability and impact consequence in assigning its Levels. Find the Torino Scale categories’ full descriptions here.
In detail for the current probability, the NASA JPL Center for Near-Earth Object Studies now lists the 2024 YR4 probability as 0.00005 (0.005%) or 1-in-20,000 for its passage by Earth in 2032.
That’s zero, folks!
In late January, EarthSky’s Deborah Byrd interviewed asteroid expert Richard Binzel of MIT – inventor of the Torino Impact Hazard Scale – about a possible strike to Earth by asteroid 2024 YR4. He also talked a lot about the overall picture of how astronomers are keeping Earth safe from asteroid collisions. It’s fascinating stuff. Watch the video here.
Odds of impact increased before dropping
Not long after 2024 YR4’s discovery – in late 2024 – astronomers were saying there was a 1-in-83 chance of a strike. Then the odds went to 1 in 53, then 1 in 43, then 1 in 38, and – at worst – the odds were 1 in 32. That became the new record for an asteroid on the Torino scale, beating the infamous asteroid Apophis in 2004. As we have been saying all along:
It’s likely that the odds will go down to zero with further data.
The new estimates for 2024 YR4 – showing it is no longer considered a possible threat to Earth – come from NASA’s Center for Near Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory in Pasadena, California.
Asteroid 2024 YR4 is moving away from us
Asteroid 2024 YR4 is 116 million miles (187 million km) away and getting farther every second. Some observers noticed the asteroid will be somewhat “close” to the Lucy spacecraft, so its team checked to see if 2024 YR4 would be observable by the spacecraft. But – at its closest to Lucy – the asteroid will still be too faint for the spacecraft’s L’LORRI instrument to detect.
What is the Torino scale?
The IAU has been using the Torino Impact Hazard Scale since 1999 to categorize asteroids that could potentially hit Earth. An object with a score of 3, as 2024 YR4’s rating was for a while, is in the yellow zone. This means the object merits attention by astronomers and the public. The description of a score of 3 reads:
A close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of localized destruction. Most likely, new telescopic observations will lead to reassignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away.
In fact, most new asteroids that get listed on the Torino scale have their likelihood of hitting Earth go up with more observations … until it drops to zero. That’s because the uncertain path of the asteroid is wide and more observations shrink the path, making it look more likely, until the path shrinks enough to show that it will not cross Earth’s. And that’s what happened with asteroid 2024 YR4 also.
Asteroid Potential Impact Warning Notification
Because the asteroid passed a slim threshold of hitting Earth, it triggered a Potential Impact Warning Notification on January 29, 2025. That warning came from the International Asteroid Warning Network (IAWN), a global collaboration of observatories, scientific institutions and other interested parties coordinated by NASA.
On January 29, the impact probability was a mere 1.3% as calculated by CNEOS and ESA’s Near Earth Objects Coordination Centre in Frascati, Italy, in cooperation with the NEO Dynamic Site (NEODyS-2), also in Italy.
The notice gave the potential date of impact as December 22, 2032, and listed possible impact locations across the eastern Pacific, northern South America, into Africa and southern Asia. If it were to strike Earth, it would cause “severe blast damage.” Specifically, the blast damage could occur as far as 30 miles (50 km) from the site of impact.
Try out an asteroid impact simulator
DART
If someday we find an asteroid that is on a collision course with Earth, we’ll be somewhat prepared. We’ve already sent a mission to hit and move an asteroid as a test of our planetary defense system. That mission was the Double Asteroid Redirection Test (DART), which impacted an asteroid’s moon named Dimorphos in 2022.
And Dimorphos was much larger than asteroid 2024 YR4, at 525 feet (160 meters) across.
Bottom line: NASA said on March 5, 2026, that asteroid 2024 YR4 will not strike the moon in 2032. The asteroid had a low probability of a future strike, but new observations have now ruled that out.
Via
International Asteroid Warning Network
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