“City Killer” Asteroid No Longer a Threat to Earth, But Moon Faces Rising Impact Risk
A potentially devastating asteroid, initially assessed as a significant threat to Earth, has been largely ruled out as an impactor, though new data indicates a growing probability of it colliding with the Moon in 2032.
The asteroid, designated 2024 YR4, first gained international attention on December 27, 2024, when it was discovered by the “Asteroids” Earth Impact Warning System (ATLAS) located in Rio Urtado, Chile. Initially classified as a “city killer” due to its size, the asteroid quickly rose to the top of the Dulin hazard index, a system used to assess the risk posed by near-Earth objects. At one point, the probability of impact with Earth reached 3.1%.
However, according to scientists, more precise observations in late February 2025 significantly reduced the risk to our planet, bringing it down to almost zero. The focus has now shifted to the Moon, Earth’s celestial neighbor.
Following Earth’s reprieve, the likelihood of 2024 YR4 impacting the Moon has been steadily increasing. Observations from NASA’s James Webb Space Telescope (JWST) in May 2024 provided crucial data for refining the asteroid’s orbital path. A team led by Dr. Andy Rivkin, in collaboration with the Johns Hopkins University Applied Physics Laboratory, utilized the telescope’s near-infrared camera to conduct accurate observations.
Analysis of the JWST data, combined with expertise from NASA’s Near-Earth Celestial Research Center, reveals that the probability of the asteroid striking the Moon on December 22, 2032, has risen from 3.8% in March to 4.3% in May. NASA officials stated that the new data has improved the accuracy of daily position predictions for the asteroid by 20%.
The asteroid is estimated to be between 174 and 220 feet in length—roughly 53 to 67 meters—equivalent in size to 10 to 15 tall buildings. NASA assures the public that even if 2024 YR4 were to collide with the Moon, it would not alter the Moon’s orbit or pose any threat to Earth.
Currently, 2024 YR4 is too far from Earth to be observed, orbiting the sun. NASA plans to re-study the asteroid when it returns to the vicinity of Earth in 2028, providing another opportunity to refine its trajectory calculations. The agency intends to leverage this close approach to gather additional data and further assess any potential risks.
