Webb Telescope Raises Moon Impact Odds for “City-Killer” Asteroid 2024 YR4
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Asteroid’s odds of hitting the Moon have now more than doubled
Asteroid 2024 YR4 will fly by Earth on December 22, 2032. NASA and ESA now only give a very slim chance of any threat from it. New observations have, again, increased this asteroid’s odds of smashing into the Moon. That probability now sits at 1 in 120,000, but in 2047, a full 15 years after the 2032 encounter.
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.
James Webb telescope ups the odds that ‘city-killer’ asteroid 2024 YR4 will hit the moon in 2032
Asteroid 2024 YR4 is a building-size space rock measuring between 174 and 220 feet (53 to 67 meters) in diameter. New observations with JWST’s Near-Infrared Camera allowed scientists to calculate the space rock’s trajectory with the greatest precision yet. The new predictions suggest there’s a 4.3% chance that the asteroid will collide with the moon on Dec. 22, 2032 — up from the 3.8% odds of a lunar impact reported after JW ST initially imaged the asteroid in March. The asteroid will return to Earth’s cosmic doorstep again in 2028, but there is no risk of an Earth impact anytime in the foreseeable future, NASA says.
An illustration of an asteroid making a close approach to Earth, as asteroid 2024 YR4 is expected to do in 2032. | Credit: Maciej Frolow via Getty Images
The James Webb Space Telescope (JWST) has taken its final look at the potentially hazardous asteroid 2024 YR4, at least until the potentially hazardous space rock darkens Earth’s cosmic doorstep again in 2028. The latest observations reveal that, while Earth faces no risk of impact from the asteroid for the foreseeable future, the moon might not be so lucky.
The new observations, taken with JWST’s Near-Infrared Camera in May, allowed scientists to calculate the space rock’s trajectory with the greatest precision yet, according to a NASA statement . The new predictions suggest there’s a 4.3% chance that asteroid 2024 YR4 will collide with the moon on Dec. 22, 2032 — up from the 3.8% odds of a lunar impact reported after JWST initially imaged the space rock in March.
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“As data comes in, it is normal for the impact probability to evolve,” NASA representatives wrote in the statement. “NASA expects to make further observations when the asteroid’s orbit around the Sun brings it back into the vicinity of Earth in 2028. ”
Asteroid 2024 YR4 is a building-size space rock measuring between 174 and 220 feet (53 to 67 meters) in diameter — about as wide as the Leaning Tower of Pisa is tall. If an asteroid this size were to impact Earth, it could wipe out a city with the equivalent force of 500 Hiroshima bombs, Live Science previously reported . (Again, there is no risk of an Earth impact anytime in the foreseeable future.)
The asteroid was first discovered in December 2024, when astronomers realized that its orbit around the sun routinely crosses Earth’s. Early projections of its trajectory revealed a potential collision course with Earth in 2032, with the odds of an impact peaking at 3.1% in February.
Further observations with JWST and ground-based telescopes soon helped scientists hone the rock’s trajectory, bringing the odds of an Earth impact down to zero .
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Related: NASA’s most wanted: The 5 most dangerous asteroids to Earth
The range of possible locations — represented by yellow points — of 2024 YR4 on Dec. 22, 2032. The range decreased from April to June as NASA gained more data and improved their certainty of the asteroid’s position. | Credit: NASA/JPL Center for Near-Earth Object Studies
At the same time, the chances of the meaty space rock striking the moon have steadily climbed. Given the rock’s size, a collision with the moon would create a new crater but would not be devastating to Earth’s satellite. In fact, some scientists are welcoming it as a valuable exercise in asteroid impact prediction.
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NASA issues urgent update on ‘city killer’ asteroid heading towards the moon in 2032
There’s now a 4.3 per cent chance that 2024 YR4 will smash into the moon on December 22, 2032, according to NASA. The impact event could be visible from Earth as a bright flash of light, as lunar material is ejected into space. If the space rock were to hit Earth, it would create a blast equivalent to detonating 7.7 megatons of TNT and leave a 3,000-foot-wide crater in the ground. The shockwave radiating out from the impact would wipe out an area the size of a major city, which is why it has been designated a ‘city-killer’ Only discovered at the end of last year, the asteroid is somewhere between 174 and 220 feet (53 and 67 metres) in diameter – around the same size as a Boeing 747. It is currently on a wide ‘elliptical’ (not perfectly circular) orbit around the sun, while is taking it even further from us before it comes back around. NASA has been relying on observations from the James Webb Space Telescope (JWST), which is positioned 1 million miles away from us.
But NASA has raised the odds of it hitting the moon in just seven years’ time.
According to the space agency, there’s now a 4.3 per cent chance that 2024 YR4 will smash into the moon on December 22, 2032.
The impact event could be visible from Earth as a bright flash of light, as lunar material is ejected into space.
Only discovered at the end of last year, 2024 YR4 is somewhere between 174 and 220 feet (53 and 67 metres) in diameter – around the same size as a Boeing 747.
If the space rock were to hit Earth, it would create a blast equivalent to detonating 7.7 megatons of TNT and leave a 3,000-foot-wide crater in the ground.
The shockwave radiating out from the impact would wipe out an area the size of a major city, which is why it has been designated a ‘city-killer’.
Fortunately, the chance of it hitting Earth is effectively nil, but the new NASA observations increase the likelihood of it hitting the moon.
The ‘city killer’ asteroid 2024 YR4 may not be on a collision course with Earth anymore . But NASA has raised the odds of it hitting the moon in just seven years’ time (stock image)
NASA has raised the odds of asteroid 2024 YR4 hitting the moon in just seven years time. Captured here is 2024 YR4 as observed by the Magdalena Ridge telescope in New Mexico, January 27, 2025
Impact probability 4.3 per cent: The chances of the rock hitting the moon will likely continue to rise and fall. This NASA image shows the range of possible locations – represented by yellow points – of 2024 YR4 on December 22, 2032
The new odds are slightly raised from the previous 3.8 per cent chance of 2024 YR4 colliding with the moon, according to NASA.
‘As data comes in, it is normal for the impact probability to evolve,’ said Molly Wasser, public affairs officer for NASA’s Planetary Defense Coordination Office.
At more than 30 million miles away, asteroid 2024 YR4 is now too distant to detect with telescopes on Earth.
So NASA has been relying on observations from the James Webb Space Telescope (JWST), which is positioned in space about 1 million miles away from us.
Asteroid 2024 YR4 is currently on a wide ‘elliptical’ (not perfectly circular) orbit around the sun, taking it even further from us before.
Further updates will not be possible until 2028 when the space rock comes back around towards Earth and becomes bright enough to be detected again.
Bu before it escaped from its view, JWST managed to collect one more observation of the object, made using its near-infrared camera last month.
‘With the additional data, experts from NASA’s Center for Near-Earth Object Studies at the agency’s Jet Propulsion Laboratory in southern California further refined the asteroid’s orbit,’ said Wasser.
Asteroid 2024 YR4 is currently on a wide ‘elliptical’ (not perfectly circular) orbit around the sun, while is taking it even further from us before it comes back around. This image shows the orbit 2024 YR4 in purple with the sun in the centre and orbits of planets (Mercury = cyan; Venus = yellow; Earth = dark blue; Mars = red). Note the asteroid’s position (purple dot) in relation to Earth (dark blue dot) about a month before an impact might happen
What do we know about 2024 YR4? First detected: December 27, 2024 Estimated size: 174-220 feet (53-67 metres) Speed relative to Earth: More than 30,000 miles per hour Date of possible moon impact: December 22, 2032 Probability of impacting the moon: 1-in-23 (4.3 per cent) Advertisement
When it zooms back towards the inner solar system, the asteroid will reach an astonishing 85 million miles per hour (38,000 km per second).
Asteroids speed up as they approach the sun because of the increased gravitational pull from the sun as they get closer – a bit like an object travelling faster the closer it gets to the ground on Earth.
In the event that the asteroid did hit the moon, it would not alter our natural satellite’s orbit around Earth, according to NASA.
However, it would create a huge crater, ejecting rocky lunar material into space, and generating a bright flash, which should be visible from Earth.
The impact event would be the first time scientists could watch a known asteroid create a lunar crater in real-time.
The data gathered from this impact could help scientists understand more about other craters on the lunar surface.
It is worth nothing that there is a 95.7 per cent chance that it won’t hit the moon at all, as it stands – and the probability will likely continue to rise and fall.
This image provided by the European Space Agency on April 2, 2025, captured by NASA’s James Webb Space Telescope, shows asteroid 2024 YR4
Asteroid 2024 YR4 is about the same size as the Tunguska asteroid, which caused the largest impact event in recorded history when it shot through Earth’s atmosphere in 1908, flattening 830 square miles (2,150 square km) of forest (pictured)
Asteroid 2024 YR4 was discovered on December 27, 2024 – and soon became a global matter of concern.
2024 YR4 set alarm bells ringing at the world’s space agencies in February when its probability of hitting Earth reached a peak of one-in-32, or 3.1 per cent.
Thankfully, about a week later, the odds were vastly downgraded just 0.0039 per cent, or one in 26,000.
Asteroid 2024 YR4 is thought to be at least the same size as the Tunguska asteroid – which had an estimated diameter of 130 feet, according to NASA.
Tunguska caused the largest impact event in recorded history when it shot through Earth’s atmosphere in 1908, flattening 830 square miles (2,150 square km) of forest.
Many lost consciousness and at least three people passed away as a direct consequence of the Tunguska event, according to a 2019 study.
Experts are concerned that we may detect a civilization-threatening Earth-bound asteroid too late, with not enough time for a mission to knock it off course.
NASA raises the odds that an asteroid could hit the moon in 2032
Asteroid 2024 YR4 was once considered the highest impact risk to Earth ever recorded. A slight increase in the chance that it could impact the moon in 2032. Even if a collision occurs, “it would not alter the moon’s orbit,” NASA says. The asteroid is estimated to be about 174 to 220 feet long (53 to 67 meters), or about the size of a 10-story building.. Data from telescopes in Chile and Hawaii recently suggested the space rock originated in the central main belt between Mars and Jupiter and gradually shifted into a near-Earth orbit. It will swing back into view in 2028, giving scientists another chance to observe the asteroid using both JWST and ground-based telescopes. It was “an actual end-to-end exercise” for how we might respond to a potentially hazardous asteroid in the future, said one astronomer.
Although now too distant to observe from Earth, the asteroid briefly came into view in May for the James Webb Space Telescope (JWST). Using data from the telescope’s Near-Infrared Camera, a team led by Andy Rivkin of the Johns Hopkins Applied Physics Laboratory refined predictions of where 2024 YR4 will be on Dec. 22, 2032 by nearly 20%. That revised trajectory nudged the odds of a lunar impact from 3.8% to 4.3%, according to a NASA update.
“As data comes in, it is normal for the impact probability to evolve,” the statement read. Even if a collision occurs, “it would not alter the moon’s orbit.”
Astronomer Pawan Kumar, a former researcher at the Indian Institute of Astrophysics in Bengaluru, agrees the moon is safe, noting a collision with the moon “won’t be a cause for concern” because any moon debris blasted into space from the impact “blow up in Earth’s atmosphere if any of it makes it to near-Earth space.”
First detected on Dec. 27 last year, 2024 YR4 is estimated to be about 174 to 220 feet long (53 to 67 meters), or about the size of a 10-story building. The asteroid quickly grabbed headlines for having more than a 1% chance of striking Earth, the highest recorded for any large asteroid. Follow-up observations in January and February saw the impact risk climb from 1.2% to a peak of 3.1%.
Yellow points show possible locations of asteroid 2024 YR4 on Dec. 22, 2032. As new data is gathered from April to June, the uncertainty in its path decreases. Earth lies near the center of the white circle, which marks the moon’s orbit. (Image credit: NASA/JPL Center for Near-Earth Object Studies)
The asteroid’s projected trajectory at the time suggested it could cause blast damage across a wide potential impact zone, spanning the eastern Pacific, northern South America, Africa and southern Asia. If it enters Earth’s atmosphere over the ocean, NASA estimated it would be unlikely to trigger significant tsunamis, but an airburst over a populated city could shatter windows and cause minor structural damage.
However, the impact risk dropped sharply as additional orbital data came in. By Feb. 19, the probability had fallen to 1.5%, and then to 0.3% the next day. On Feb. 24, NASA announced an official “all clear” on social media, reporting the impact probability had dropped to just 0.004% and that the asteroid is “expected to safely pass by Earth in 2032.”
Further analysis has since allowed scientists to rule out any risk to Earth, not only in 2032 but from all future close approaches as well. Data from telescopes in Chile and Hawaii recently suggested the space rock originated in the central main belt between Mars and Jupiter and gradually shifted into a near-Earth orbit.
An illustration of an impact on the moon. (Image credit: Mark Garlic/Science Photo Library via Getty Images)
Since mid-April, the asteroid has been too far away and too faint to be seen from Earth. It will swing back into view in 2028, giving scientists another chance to observe the asteroid and further refine its orbit using both JWST and ground-based telescopes. In particular, scientists will aim to gather more data on its shape and composition, which are key factors in understanding both its behavior and potential impact effects.
While 2024 YR4 no longer poses any danger, it provided scientists with a rare, real-world opportunity to rehearse the full scope of planetary defense strategy, ranging from initial detection and risk analysis to public messaging. It was “an actual end-to-end exercise” for how we might respond to a potentially hazardous asteroid in the future, said Kumar.
“2024 YR4 is a tailor-made asteroid for planetary defense efforts,” he said. “It has everything it takes to get our attention.”
NASA issues update on size of ‘city-killer’ asteroid 2024 that could smash into the Moon
NASA issues update on size of ‘city-killer’ asteroid 2024 that could smash into the Moon. The space rock, which is roughly the size of a 10-story building, was previously predicted to be heading for Earth. However, recent updates from NASA’s Center for Near-Earth Object Studies indicate an increased likelihood that it could strike the Moon instead. Despite the risk, NASA reassures that such an impact would not alter the Moon’s orbit. As the asteroid continues its journey around the Sun, scientists will be able to refine their predictions on whether it will hit the Moon in 2032. For now, though, the risk remains low and won’t pose any serious consequences for the Moon’S orbit. For more information about asteroid 2024 YR4, visit NASA’s Near-earth Object Studies website or see www.nasa.gov.uk/nearearth-object-studies. For confidential support call the Samaritans in the UK on 08457 90 90 90, visit a local Samaritans branch or click here for details.
The space rock, which is roughly the size of a 10-story building, was previously predicted to be heading for Earth
Asteroid 2024 YR4, discovered in December 2024, now has a higher chance of striking the Moon in 2032, according to NASA (Image: Getty Images )
NASA has raised the odds that a massive asteroid, about the size of a 10-storey building, could collide with Earth’s Moon.
Asteroid 2024 YR4, discovered in December 2024, initially posed a potential risk to Earth in 2032. However, recent updates from NASA’s Center for Near-Earth Object Studies, based at the Jet Propulsion Laboratory, indicate an increased likelihood that it could strike the Moon instead.
As of February 2025, observations based on data from the James Webb Space Telescope and ground-based telescopes show that the chances of the asteroid hitting the Moon on December 22, 2032, have risen from 1.7 percent to 3.8 percent.
While this still leaves a 96.2 percent chance of the asteroid missing the Moon, the small possibility of a collision has caught scientists’ attention. Despite the risk, NASA reassures that such an impact would not alter the Moon’s orbit.
NASA has raised the chances that asteroid 2024 YR4, about the size of a 10-storey building, could collide with Earth’s Moon instead of Earth (Image: NASA )
In an update from NASA, experts explain that the asteroid’s size was re-evaluated using Webb’s data. Its dimensions were reduced from an earlier estimate of 131-295 feet (40-90 metres) to a more accurate range of 174-220 feet (53-67 metres)—roughly the size of a 10-storey building.
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As is common with asteroid predictions, the chances of an impact often fluctuate, rising and falling as new data comes in. Earlier, asteroid 2024 YR4 had its risk of hitting Earth initially rise to 3.1 percent in February, before dropping nearly to zero by the end of the month. The asteroid’s risk of hitting the Moon has now become the focus of NASA’s observations.
The asteroid’s size was revised to 174-220 feet (53-67 metres), roughly the size of a 10-storey building (Image: Getty Images )
Once mid-April arrives, asteroid 2024 YR4 will be too faint to observe with ground-based telescopes. However, the James Webb Space Telescope will continue monitoring it and is expected to provide further insights during a planned observation window in late April or early May 2025.
As the asteroid continues its journey around the Sun, scientists will be able to refine their predictions on whether it will strike the Moon in 2032. For now, though, the risk remains low and won’t pose any serious consequences for the Moon’s orbit.
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Andy Rivkin, principal investigator of NASA’s Webb Director’s Discretionary Time program, highlighted the importance of studying asteroid 2024 YR4, despite its low risk to Earth.
“While we are confident that 2024 YR4 will not hit Earth in 2032, there is still great value in making these observations and analysing the results,” Rivkin said.
He noted that future asteroid search programmes will uncover more potential threats, and studying YR4 helps prepare for urgent cases.
Rivkin also emphasised the collaboration in studying near-Earth asteroids: “The new observations from this observatory not only provide unique information about 2024 YR4’s size, but they also improve our understanding of its orbit and trajectory,” he added. “This helps us prepare for the next potential impact.”
Source: https://scitechdaily.com/webb-telescope-raises-moon-impact-odds-for-city-killer-asteroid-2024-yr4/