Asteroid 2024 YR4 is once again drawing attention, not for posing a threat to Earth, but for a slight increase in the probability that it could impact the moon in 2032. According to an update from NASA, the revised estimate has nudged the chances of a lunar impact from 3.8% to 4.3%, following new observations made by the James Webb Space Telescope.

From Planetary Panic to Lunar Watch

The asteroid was first detected on 27 December last year and quickly made headlines as the most concerning object on NASA’s watch list. With early projections suggesting over a 1% chance of hitting Earth, the highest ever recorded for a large asteroid, it triggered serious consideration within the planetary defence community.

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At one point in January, that probability climbed to a peak of 3.1%, prompting detailed analysis of the potential impact zone, which ranged from the eastern Pacific to parts of South America, Africa, and Asia. By late February, however, the threat had been all but ruled out. As additional tracking data came in, particularly from observatories in Chile and Hawaii, the odds of a collision dropped dramatically. On February 24, NASA issued an “all clear”, confirming that 2024 YR4 posed no threat to Earth either in 2032 or at any time in the future.

Though its Earth-bound risk has been eliminated, recent measurements using JWST’s Near-Infrared Camera allowed researchers led by Andy Rivkin at Johns Hopkins APL to tighten predictions of its path by nearly 20%. That refinement resulted in the small uptick in the probability of a lunar impact. Even if the asteroid were to strike the moon, astronomers say it would not alter the lunar orbit or present any risk to Earth. Former Indian Institute of Astrophysics researcher Pawan Kumar noted that debris would likely incinerate harmlessly in Earth’s atmosphere if it ever made the journey. Currently too distant to observe from Earth, the asteroid will become visible again in 2028, giving scientists another opportunity to study its structure and composition using both space- and ground-based instruments.

While 2024 YR4 no longer poses any real danger, its brief moment in the spotlight served as a valuable test case for the global planetary defence infrastructure, a rare opportunity to practice the full pipeline from early detection through to public reassurance.