First spotted late last year, asteroid 2024 YR4 initially caught attention due to a small chance of hitting Earth. Now, thanks to powerful new observations, scientists have refined its path, revealing an intriguing possibility: a rare lunar impact in 2032. While the risk remains low, this shift from an Earth concern to a potential Moon target is a fascinating development for asteroid trackers and researchers.
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An Unwelcome Visitor Enters the Scene
Asteroid 2024 YR4 was first detected on December 27, 2023, by the ATLAS telescope network in Chile. Early calculations placed it relatively high on the Torino Impact Hazard Scale, briefly reaching a 3.1% chance of impacting Earth in February 2024. This space rock, estimated to be between 174 and 220 feet wide (roughly the height of a 10-story building), earned the unsettling nickname “city-killer” because a strike in a populated area could cause significant damage.
However, as astronomers gathered more data from ground telescopes into early 2025, the calculated risk to Earth steadily decreased. NASA eventually issued an “all clear” for our planet as the probability dropped to a tiny fraction of a percent. But even as Earth was ruled out, attention began to shift towards our closest celestial neighbor.
JWST Provides a Sharper View
To get a more precise look at 2024 YR4’s trajectory, an international research team led by Dr. Andy Rivkin of the Johns Hopkins Applied Physics Laboratory turned to the most powerful space telescope available: the James Webb Space Telescope (JWST). In May 2024, they used Webb’s Near-Infrared Camera to track the asteroid with unprecedented accuracy.
Analyzing the data from JWST alongside information from NASA’s Center for Near-Earth Object Studies (CNEOS) dramatically improved scientists’ certainty about the asteroid’s future path. Specifically, the Webb observations refined the predicted location of 2024 YR4 on December 22, 2032, by nearly 20%. This seemingly small improvement in precision had a significant consequence for predicting potential impacts.
The Odds of a Lunar Collision Increase
With the asteroid’s route better defined, the probability of it striking the Moon on December 22, 2032, was recalculated. The new estimate increased the chance from 3.8% to 4.3%. While this is still a relatively small probability, it’s high enough to capture the interest of the scientific community.
Richard Moissi, head of the European Space Agency’s planetary defense office, noted the scientific excitement: “the possibility of getting a chance for an observation of a sizable Moon impact is indeed an interesting scenario from a scientific point of view.”
Map showing possible locations of asteroid 2024 YR4 near the Moon on Dec 22, 2032
Why a Moon Impact Matters
Should 2024 YR4 collide with the Moon, NASA confirms it would not alter the Moon’s orbit around Earth. The primary outcome would be an extremely valuable opportunity for scientific research. A medium-sized impact event like this could provide data on the Moon’s subsurface structure and the dynamics of impact cratering.
Any debris ejected from the lunar surface by such an impact is anticipated to burn up harmlessly in Earth’s atmosphere, posing no threat to people on the ground. This scenario presents a unique chance to study a significant impact event firsthand from Earth and orbit, offering insights far beyond what current lunar missions provide.
While a 4.3% chance is far from a certainty, the refined trajectory of asteroid 2024 YR4 has shifted the focus from a potential Earth concern to a compelling scientific opportunity on the Moon. Scientists will continue to track this intriguing space rock as it makes its journey towards the predicted encounter in 2032.
