Will an Asteroid Hit Earth? How NASA Tracks the Risk
Asteroid 2024 YR4 briefly had the highest impact odds NASA had seen for an object its size. Here is how those odds rose and fell, and how planetary defense works.
No known asteroid is on course to hit Earth, according to NASA’s impact monitoring. The most-watched recent case, asteroid 2024 YR4, briefly reached a 3.1% chance of hitting Earth in December 2032 before new observations ruled that out in February 2025, and NASA ruled out a 2032 impact on the Moon in March 2026.
New asteroids are found every night, and their early odds often jump before falling to zero. Knowing how the tracking works makes those headlines easier to read.
How does NASA track asteroids that could hit Earth?
NASA tracks near-Earth objects through telescope surveys that find them, a global clearinghouse that collects positions and a JPL system that calculates orbits and impact odds. The work is coordinated by NASA’s Planetary Defense Coordination Office.
- Discovery: survey telescopes scan the sky each night for moving points of light.
- Reporting: observatories send positions to the Minor Planet Center, which links them to known or new objects.
- Orbit calculation: the Center for Near Earth Object Studies (CNEOS) at JPL computes each orbit. Its Sentry system scans the next 100 years for possible impacts.
- Follow-up: more observations shrink the uncertainty in the orbit, and the impact odds are updated.
Every listed object on the CNEOS Sentry risk table is public, along with its estimated size and impact probability.
What is the Torino scale?
The Torino scale rates possible asteroid impacts from 0 to 10, combining the chance of a hit with how much damage it would do. It was adopted by the International Astronomical Union in 1999 to help explain risks to the public.
| Rating | Color | Meaning |
|---|---|---|
| 0 | White | No hazard: the chance of collision is zero or effectively zero |
| 1 | Green | Normal: a routine discovery with a predicted close pass and no unusual danger |
| 2 to 4 | Yellow | Merits attention by astronomers; public attention only if the encounter is less than a decade away |
| 5 to 7 | Orange | Threatening: a serious but uncertain threat that may call for government contingency planning |
| 8 to 10 | Red | Certain collision, from local destruction (8) to a threat to civilization (10) |
The scale’s own descriptions expect new observations to lower most low ratings back to 0. A downgrade is the normal pattern, not a sign that something was missed.
What happened with asteroid 2024 YR4?
Asteroid 2024 YR4 was discovered in late December 2024 and, for a few weeks in early 2025, had the highest impact probability NASA had recorded for an object of its size or larger. Webb telescope images later put its size at roughly that of a 15-story building.
- Jan. 27, 2025: the impact chance for Dec. 22, 2032, passed 1%, and the asteroid reached level 3 on the Torino scale.
- Feb. 18, 2025: the chance peaked at 3.1%.
- Feb. 24, 2025: new observations cut it to 0.004%, and NASA said the asteroid posed no significant threat to Earth in 2032 or beyond.
- 2025: the chance of hitting the Moon instead rose, reaching 4.3% after further tracking.
- March 5, 2026: NASA said Webb observations from Feb. 18 and 26, 2026, ruled out a lunar impact on Dec. 22, 2032.
NASA said the March 2026 update reflected a more precise idea of where the asteroid will be in 2032, not a change in its path. The details are on NASA’s 2024 YR4 page. For more on the telescope that settled the question, see our James Webb explainer.
Why do impact odds rise before they fall?
Impact odds often rise at first because a new asteroid’s orbit is known only roughly, and Earth sits inside the range of places it could be. As astronomers add observations, that range shrinks. While Earth is still inside the shrinking range, the calculated odds go up. Once the range shrinks enough to leave Earth outside it, the odds drop to near zero.
That is exactly what happened with 2024 YR4. The peak in February 2025 came just days before the odds collapsed.
What did NASA’s DART mission prove?
NASA’s DART mission showed that a spacecraft can change an asteroid’s path by crashing into it. DART hit the small asteroid Dimorphos, about 160 meters (525 feet) across, on Sept. 26, 2022. Dimorphos orbits a larger asteroid, Didymos, and neither posed any threat to Earth.
Before the impact, Dimorphos took 11 hours and 55 minutes to circle Didymos. Afterward it took 11 hours and 23 minutes, a change of 32 minutes, plus or minus about 2 minutes, according to NASA. That was the first time people had measurably changed the motion of a natural object in space.
The European Space Agency’s Hera mission is on its way to study the pair up close and measure the crater and mass of Dimorphos, which will help scientists turn DART’s result into a working method.
How much warning would we get?
For large asteroids, the warning would most likely be years or decades, because surveys have already found most of the biggest ones and none is on a collision course. Smaller objects are harder to spot and can be found only days or hours before a close pass.
Very small rocks hit the atmosphere all the time and burn up as meteors or fireballs. Our guide to fireballs and how to report them explains what to do if you see one. Keeping an eye on mission updates is easy through the sources listed in our guide on how to follow NASA missions.
Bottom line
NASA’s monitoring shows no known asteroid on course to hit Earth. Asteroid 2024 YR4 peaked at a 3.1% chance of hitting Earth in 2032 before being ruled out in February 2025, and its small chance of hitting the Moon was ruled out in March 2026. DART showed in 2022 that an impact can change an asteroid’s orbit, cutting Dimorphos’s orbit by 32 minutes.
FAQ
Is any asteroid going to hit Earth soon?
No known asteroid has a significant chance of hitting Earth, based on NASA’s impact monitoring. New objects are added to the watch list regularly, and almost all are cleared once more observations come in.
Where can I check asteroid impact risks myself?
JPL’s CNEOS Sentry table lists every object with a nonzero impact chance over the next century. ESA’s Near-Earth Object Coordination Centre keeps a similar risk list.
Will 2024 YR4 hit the Moon?
No. NASA said in March 2026 that Webb observations ruled out a lunar impact on Dec. 22, 2032.
What does a Torino scale 1 mean?
A rating of 1 is a routine discovery with an extremely low chance of collision and no cause for public concern. Most such objects are downgraded to 0 after more observations.
