Asteroid's odds of hitting the Moon have now more than doubled
New observations have, again, increased this asteroid's odds of smashing into the Moon on December 22, 2032.
Earth is safe from asteroid 2024 YR4, but fresh looks at the space rock using Webb and other telescopes have now increased its chances of impacting the Moon.
After a brief stint as the highest risk asteroid we know about, 2024 YR4 is now deemed harmless to Earth. In fact, NASA's Center for Near-Earth Object Studies (CNEOS) and the ESA's Near-Earth Objects Coordination Centre (NEOCC) now only give a very slim chance of any threat from it. That probability now sits at just 1 in 120,000, but in 2047, a full 15 years after the 2032 encounter that initially raised so many alarms.
However, based on the newest telescopic observations of 2024 YR4, its December 22, 2032 flyby may be the last time it ever passes by our planet.
The extreme sensitivity of the James Webb Space Telescope allowed astronomers to continue to observe the asteroid long after it moved beyond the capabilities of Earth-based telescopes. Using the data collected by Webb, scientists with CNEOS updated their calculations of 2024 YR4's orbital path.
Back at the end of February, when NASA had ruled out any significant danger to Earth from the asteroid, they also determined there was a 1.7 per cent chance it would strike the Moon.
The new data has now increased that probability to 4.3 per cent. That's more than double the initial chance of lunar impact.
The latest probability of impact for asteroid 2024 YR4, as of June 3, 2025, at 4.3 per cent of striking the Moon on December 22, 2032. Along the top of the image is NASA's sequence of plots generated from Jan 27 through Feb 23 showing how the asteroid's closest approach to Earh changed as observations refined its orbit. (NASA CNEOS)
A 4.3 per cent of impact still counts as a 95.7 per cent chance that it will miss the Moon. So, with it having no chance of hitting Earth on that date, 2024 YR4 could simply slip through lunar orbit with no effect at all — just a telescopic curiosity to observe as it passes by.
Still, at an estimated 65-metres wide, when 2024 YR4 was still thought to be a threat to Earth, it was (unofficially) considered to be a 'city-killer' asteroid.
It was highly unlikely to have hit anywhere inhabited. However, if it did, that size of asteroid would have caused extensive damage on a local level. For any city in the impact zone, the effects would have been catastrophic.
An estimate of the size and shape of asteroid 2024 YR4 based on telescopic observations. (NOIRLab)
For comparison, the 20-metre asteroid that exploded over Cheylabinsk on February 15, 2013 produced an airburst — a pressurized wave of air — that shattered windows across the city when it reached the ground. Tiny fragments of the asteroid rained down over the area, with the largest piece, roughly 60 cm wide and with a mass of around 300 kg, punching a hole in the frozen surface of nearby Lake Chebarkul.
The airburst that would result from 65-metre 2024 YR4 exploding would be powerful enough to level buildings. While not large enough to produce a crater, the shattered asteroid would likely include several larger pieces that would cause further damage and injuries upon striking the ground.
If 2024 YR4 does hit the Moon in 2032, with no atmosphere to slow it down, it would impact with full force, travelling at nearly 13 kilometres per second, or over 46,000 km/h.
The Waning Gibbous phase of the Moon on the night of December 22, 2032. (NASA's Scientific Visualization Studio)
If it strikes somewhere in the dark region of the surface, the impact will certainly be noticeable from Earth. It wouldn't be powerful enough to affect the Moon's orbit, or knock any significant pieces off the Moon. It would certainly leave behind a crater that an orbiting spacecraft (such as NASA's Lunar Reconnaissance Orbiter) would be able to find, though.
According to NASA, as of now, 2024 YR4 has moved beyond even Webb's ability to observe it, as it is now too close to the Sun. The next 'encounter' with the asteroid will be in 2028, with its closest pass at that time being around 20 times farther than the Moon. Telescopes should be able to find and track it, though, adding more to our knowledge of its orbit, and potentially locking down whether it will hit or miss the Moon when it returns four years later.
(Thumbnail image was produced by the author, using photo-editing software, by adding a 3D computer model of asteroid 2024 YR4 to a background image of the Moon taken during NASA's Artemis 1 mission.)