Weeks of uncertainty around asteroid 2024 YR4 kept lunar scientists alert. NASA now reports that this near-Earth traveller will glide past the Moon, rather than threaten its battered surface yet again.
Fresh measurements from space-based observatories gave orbit calculators the extra arc they needed to shrink trajectory uncertainties for 2024 YR4. Using James Webb Space Telescope data, NASA derived a refined orbital solution that rules out impact during the Dec. 22 2032 flyby, driving risk to zero.
Webb observations sharpen asteroid 2024 YR4’s position for 2032
During two observing sessions on Feb. 18 and 26, 2025, NASA’s James Webb Space Telescope measured asteroid 2024 YR4 as it receded from Earth, extending the tracking arc beyond what ground-based observatories in spring 2025 could achieve.
These Webb measurements refined the asteroid’s trajectory and tightened forecasts for its Dec. 22, 2032 position relative to the Moon. By pushing sensitivity to record-low signal levels, mission teams secured faint asteroid detections during narrow observation windows in 2025, achieving improved ephemeris precision that feeds directly into NASA’s Near-Earth Object Studies calculations at the Jet Propulsion Laboratory.
From a 4.3% lunar impact estimate to a safe flyby
Early calculations in January 2025, based on a short observation arc, indicated that asteroid 2024 YR4 carried a 4.3% chance of striking the Moon on Dec. 22, 2032, prompting careful re-examination by NASA dynamicists.
Once Webb observations and added ground-based data were incorporated, the orbit solution showed that the asteroid will miss the lunar surface by a wide margin. Current models place the body at about 13,200 miles from the Moon’s center at closest pass, a distance described as the 13,200 miles closest approach, after an intensive lunar impact probability revision and marked uncertainty ellipse shrinkage, while confirming that its overall orbital path not changed in response to any known forces.
How NASA tracks near-Earth objects when ground telescopes lose sight
Asteroid 2024 YR4 entered NASA’s catalog late in 2024 after a survey telescope in Chile picked up its slow drift against background stars. The alert traced back to the NASA-funded Asteroid Terrestrial-impact Last Alert System, cited as the ATLAS discovery in Chile in internal reports.
As 2024 YR4 grew faint and slipped beyond the reach of many ground telescopes, tracking responsibility shifted toward orbit modelers and specialists working with NASA’s deep-space assets. Their strategy blended targeted space-based follow-up by James Webb with sophisticated JPL risk assessment models and tight global observatory coordination, ensuring that predictions of the asteroid’s future passes remain tied to every available photon collected in early 2025.
