Now the astronomical community has shifted its attention to Asteroid 2024 YR4. This new celestial body was first imaged on December 27, 2024, with the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey telescope at Río Hurtado, Chile. Its diameter was measured to be anywhere from 53 to 67 meters. At first, it carried a minimal chance of hitting Earth on December 22, 2032. By March 2025, astronomers were able to determine that an Earth impact was impossible for that date.
As of this writing, asteroid 2024 YR4 has a risk 4% of hitting the Moon on that date. However, the asteroid is moving farther away from Earth, making it dimmer and dimmer. It will be back for closer inspection in mid-2028. The odds of a lunar impact going there should be consistent until then.
Astronomers are especially excited about this asteroid because celestial events like these are so rare. Furthermore, while the immediate impact of the event would be very visible from Earth, it holds wider significance for protecting Earth from near-Earth objects.
Discovery and Initial Observations
The finding of asteroid 2024 YR4 pointed out the extreme difficulty astronomers have with finding and tracking celestial bodies. For example, the asteroid approached Earth from the daytime side, backlit by sunlight, which complicated and increased the time required for its detection. That’s because ground-based telescopes wouldn’t be able to spot the asteroid until it was already within striking range.
As Richard Moissl, an astronomer and near-Earth object program manager for the European Space Agency, pointed out to me, that’s misconception number one. Had the NEOMIR infrared telescope been in operation while the asteroid was approaching, it would have spotted 2024 YR4 roughly one month earlier than ground-based observatories. This earlier detection would have permitted for more thorough assessment of its path and possible dangers.
“We looked into how NEOMIR would have performed in this situation, and the simulations surprised even us,” – Richard Moissl
The NEOMIR telescope, designed to act as an early-warning system for asteroids approaching from the Sun’s direction, would have provided critical data on the asteroid’s size and trajectory much sooner. Moissl emphasized the importance of this information:
“As an infrared telescope, like Webb, NEOMIR would have also immediately given us a much better estimate of the asteroid’s size, which is very important for assessing the significance of the hazard.” – Richard Moissl
Current Predictions and Implications
As more observations have come in, astronomers have watched the probability of a lunar impact slowly rise. The latter observations measured a 4% impact probability with impact on lunar surface on 12/22/2032. While this seems like a small improvement, it is important enough that it should be praised.
Asteroids of this size hit Earth only once every few thousand years on average. When they do hit, they are capable of inflicting catastrophic damage to densely populated cities. Asteroid 2024 YR4 is not a threat to hit Earth, so no need to panic. It’s promise to change the Moon raises questions about how that game-changing event would be unfolding.
Moissl explained that while a lunar impact remains unlikely, scientists are eager to study its potential outcomes:
“It is a very rare event for an asteroid this large to impact the moon—and it is rarer still that we know about it in advance. The impact would likely be visible from Earth, and so scientists will be very excited by the prospect of observing and analyzing it. I am sure that detailed computational simulations will be done over the next few years.” – Richard Moissl
He noted that while it would create a new crater on the Moon’s surface, predicting the amount of material ejected into space remains challenging.
“It would certainly leave a new crater on the surface. However, we wouldn’t be able to accurately predict in advance how much material would be thrown into space, or whether any would reach Earth.” – Richard Moissl
Future Monitoring and Technological Advancements
Meanwhile, asteroid 2024 YR4 is still cruising through space. In return, astronomers are preparing for future observations that will help them narrow down their predictions about its trajectory and possible impacts. The ability to monitor these types of entities can far exceed capabilities today if we use technology to our advantage.
The NEOMIR telescope would be the first purpose-built observatory to detect and classify near-Earth objects. By providing earlier detection capabilities and accurate measurements, it could revolutionize how astronomers track and assess potential threats from asteroids.
The European Space Agency (ESA) has been at the forefront of this initiative, emphasizing that NEOMIR will serve as a crucial tool for planetary defense:
“The NEOMIR orbiting observatory will act as an early warning system to detect and monitor any asteroid coming towards Earth from the Sun’s direction.”