NASA Update on the Size Estimate and Lunar Impact Probability of Asteroid 2024 YR4

Since its discovery in the latter half of 2024, asteroid 2024 YR4—a near-Earth object (NEO)—has received a lot of attention from astronomers as well as the general public. NASA has now provided a significant update on the NEO. New observations have eliminated the risk of a future Earth impact, which was the source of the initial concern. However, scientists now report a slightly increased probability that the asteroid could strike the Moon in 2032.

From Earth Threat to Lunar Possibility

NASA's planetary defense monitoring systems discovered asteroid 2024 YR4 for the first time in December 2024. With a projected close approach on December 22, 2032, its orbital path appeared to pose a minimal threat to Earth at the time. Using both ground-based telescopes and space-based instruments, additional research was conducted after initial models predicted a chance of less than one percent of the object hitting Earth. NASA has now officially ruled out the possibility of the asteroid hitting Earth during its 2032 flyby thanks to improved orbital data. However, the focus has now shifted to our celestial neighbor. The likelihood of a lunar impact is now estimated to be 3.8%, which is more than double the previous estimates. While this still represents a low chance, it’s significant enough to interest the scientific community, especially given the increasing efforts to monitor and understand the behavior of potentially hazardous asteroids.

How Big is 2024 YR4?

The key to understanding the potential consequences of an impact lies in the asteroid’s size. When 2024 YR4 was initially discovered, estimates of its diameter varied widely, ranging from 50 to 150 meters due to limited data. However, the James Webb Space Telescope's (JWST) recent infrared observations have significantly reduced that range. The most recent report from NASA states that the size of 2024 YR4 is now estimated to be between 174 and 220 feet (53 and 67 meters) across, or about the size of a building with 10 to 20 stories. This puts it in the same category as the Tunguska event object in terms of potential energy, which was one of the most powerful impact events ever recorded and wiped out a forest in Siberia in 1908. If 2024 YR4 were to collide with the Moon, the resulting explosion could produce a crater 500 to 1,000 feet in diameter (150 to 300 meters), depending on impact speed and angle.

What Would a Lunar Impact Mean?

Since the Moon is uninhabited, there is no risk to life or infrastructure, but a possible lunar impact would be a rare and important event for science. According to NASA scientists, such a collision would be visible from Earth with the right equipment, and possibly even to amateur astronomers under proper conditions. It could also be captured by the various satellites and observatories currently monitoring the Moon’s surface, including instruments operated by NASA, ESA, and private space agencies.

More importantly, the impact would give scientists a unique chance to study real-time crater formation and surface responses to high-velocity impacts — data that is difficult to simulate accurately on Earth.

"This would be a once-in-a-generation opportunity," said Dr. Laura Daniels, a planetary geologist at NASA’s Jet Propulsion Laboratory. "If it happens, the scientific payoff would be enormous."

What Happens Next?

NASA emphasized that there is no cause for alarm, and that the asteroid is being monitored closely as part of the agency’s broader planetary defense strategy. Continued tracking and refinement of its orbit are ongoing, and more observation windows are scheduled in the coming years as 2024 YR4 becomes more visible.

In the meantime, the agency is also preparing to use the event — should it occur — to test observational technologies and potential mitigation strategies. Although this asteroid does not pose a threat to Earth, it provides an ideal scenario for practicing international response coordination and data collection techniques for future events that might.

The Bigger Picture: Planetary Defense

The study of near-Earth objects has gained increased prominence over the last decade. Projects like NASA’s DART (Double Asteroid Redirection Test) mission — which successfully altered the trajectory of the asteroid moonlet Dimorphos in 2022 — highlight the growing interest and capability in planetary defense.

Asteroid 2024 YR4 is a prime example of how space agencies can work proactively, identifying risks early and responding with data-driven plans. As observatories and organizations from all over the world contribute to the ongoing evaluation of this object's path, it also demonstrates the significance of international cooperation. Conclusion

The latest update from NASA confirms that Earth is safe from asteroid 2024 YR4, at least for the foreseeable future. However, the increased chance of a lunar impact in 2032 has opened up a new frontier of scientific curiosity and preparation. With cutting-edge tools like the James Webb Space Telescope and global collaboration at play, humanity is more prepared than ever to monitor, understand, and, if needed, defend against the dynamic threats of space.

Whether it strikes the Moon or passes quietly by, 2024 YR4 is already proving to be a valuable object of study in our ever-evolving understanding of the cosmos.