Asteroid 2024 YR4 is an asteroid with an estimated diameter of 60 meters that at one point was thought to pose an impact risk to the Earth. Ongoing telescopic observations have refined our knowledge of its path, and now we know it will miss our planet. But there is still (as of June 2025) a 4% chance that the asteroid will strike the Moon.
In a paper submitted in June 2025 to the American Astronomical Society journals (a preprint of the paper is available at this link or here), the possibility that material ejected from the Moon by an impact from asteroid 2024 YR4 is examined from the point of view of the risk it poses to Earth-orbiting satellites. It is found that small (0.1 to 10 millimeter) sized particles from the Moon, the same size that produce meteors (also known as "shooting stars" or "falling stars") in our atmosphere every night, could result in 10 to 1000 times increased rate of these particles near the Earth a few days after the asteroid impact, if it does. This could produce an eye-catching meteor shower, but there is no danger to the surface of the Earth. However, satellites in Earth orbit could face an increased risk of being hit and damaged by these particles.
Additionally, the material could affect operations of Moon-orbiting spacecraft, including proposed systems like Lunar Gateway. As well, much of the material lifted by the asteroid impact (if it occurs) will fall back to the Moon. This could affect surface operations of landers, rovers and of astronauts of the Artemis program.
Video illustrations of the delivery of lunar material from Moon to Earth
A computer simulation of the delivery of material from the Moon to the Earth is below.
If 2024 YR4 strikes the Moon in 2032, it will (statistically speaking) be the largest impact in approximately 5000 years. The delivery of ejecta escaping the Moon to near-Earth space is highly sensitive to the precise impact location, but the impact corridor as understood at this writing does allow for delivery efficiencies of up to 10%. This would result in particle fluxes at Earth of 10 to 1000 times their background values, and could produce effective exposures equivalent to years in space over just a few days. The resulting meteor shower at Earth could be eye-catching, with rates orders of magnitude above usual background rates but meteor light production will be reduced by their relatively low in- atmosphere speeds. The travel time from lunar impact to Earth is typically several days but does depend on the precise location of the impact if it even occurs, which probably cannot be determined until the asteroid returns to visibility in 2028. Material persisting in Earth orbit for longer times could also present a hazard. this analysis highlights that issues of planetary defense extend beyond just the effects of impacts on Earth’s surface.
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