Recent astronomical analyses indicate that asteroid 2024 YR4, a small near-Earth object, poses a potential impact threat to the Moon in December 2032, with a current estimated probability of 4.3%. The Earth remains outside any significant risk for over 100 years, according to updated trajectory calculations.

Initial observations at the beginning of 2025 raised concerns when a short-term risk assessment indicated a greater than 3% chance that the asteroid could impact Earth on December 22, 2032. However, by late February 2025, this possibility was ruled out through coordinated global observational efforts employing large ground-based and space-based telescopes. The James Webb Space Telescope (JWST) played a key role in these assessments, providing high-resolution data that enabled refined orbital modeling.

New analysis of JWST observations reveals that while Earth is no longer at risk from 2024 YR4, the asteroid has a 4.3% probability of impacting the lunar surface during its close approach in December 2032. This event would mark the first opportunity to observe an impact on the Moon in real time under controlled scientific monitoring.

The current best estimate places the diameter of 2024 YR4 at approximately 60 meters, with a margin of uncertainty of ±7 meters. Based on artillery-based scaling laws—where crater formation typically yields a final diameter about twenty times that of the impacting body—a lunar impact would produce an excavation crater of roughly 1,200 meters in diameter. This is comparable to the well-known Meteor Crater in Arizona.

If such an impact were to occur, it would generate a luminous flash briefly reaching the brightness level of Jupiter as seen from Earth. The resulting glow from the impacted region on the Moon—illuminated under a two-thirds illuminated waxing phase—would be visible for several hours. However, due to lunar geometry at that time, observers in central Europe would not have visual access, as the Moon would remain below the horizon.

Simulations conducted by a research team led by Yifan He from Tsinghua University in Beijing predict that, should impact occur, up to 10,000 tons of lunar material could be ejected at velocities exceeding the Moon’s escape velocity of 2.4 km/s. This ejection would significantly increase the flux of transient debris in the Earth-Moon space environment, raising the collision risk for orbiting spacecraft and satellites.

Additional physical characterization was achieved through observations using the Gemini North 8-meter telescope. These data confirm that 2024 YR4 is a silicate-rich S-type asteroid with an elongated, slightly flattened keystone-like shape. Furthermore, detailed rotational analysis by Andrew Rivkin’s team at Johns Hopkins University in Maryland reveals a remarkably rapid rotation period of just 19.46 minutes.

This fast spin rate indicates that the object is structurally coherent and likely composed of solid rock rather than being an aggregate rubble pile. A loosely bound asteroid would disintegrate under such rotational forces due to insufficient self-gravitational cohesion to counteract centrifugal forces, suggesting a monolithic composition despite its size.

These findings underscore the importance of continued monitoring of 2024 YR4 through at least 2028, when further observational data will provide definitive clarification on the impact probability. The potential for an observed lunar impact offers a unique scientific opportunity to study impact dynamics in situ and assess secondary effects such as ejecta dispersion and long-term space environment changes.

---

Filed under: Astronomy - @ February 4, 2026 8:13 am