NASA discovers asteroid's new target: the moon

The Asteroid That Could Hit the Moon

An asteroid once labeled a “city killer” is now making headlines again, but this time, it’s not Earth that’s in the crosshairs. Instead, scientists are closely monitoring the potential for an impact on the moon. This asteroid, known as 2024 YR4, has become a key case study for NASA’s planetary defense systems.

A Brief History of 2024 YR4

Discovered in December 2024, 2024 YR4 initially raised concerns due to its size and trajectory. At one point, the asteroid had a 3.1% chance of hitting Earth, which earned it a 3 out of 10 rating on the Torino scale—a classification used to assess the risk of an asteroid impact. This made it the most threatening asteroid observed in over two decades.

Davide Farnocchia, a navigation engineer at NASA’s Jet Propulsion Laboratory, recalls the moment his team had to alert astronomers about the potential threat. “We had to notify them and say, ‘Look, this object should get higher priority in your schedule for observing asteroids tonight,’” he said. “We needed more data to hopefully prove that it would move away from the Earth.”

From Earth to the Moon

As more data became available, the probability of an Earth impact dropped significantly. However, the story didn’t end there. Scientists began to focus on the moon as a potential target. By May 2025, NASA’s James Webb Space Telescope captured the last look at 2024 YR4 before it slipped too far from view. The data refined its projected path for December 22, 2032, and increased the odds of a lunar impact to 4.3%.

Farnocchia emphasized that while the moon is smaller than Earth, it’s still a large body. “Even an asteroid of 200 feet is not going to do much to it,” he said. “It wouldn’t alter the motion of the moon.” Although a 4.3% chance sounds notable, it’s still considered low by risk standards. Still, Farnocchia noted that it’s unusual to see the moon become a potential target at all.

What Would Happen If It Hit the Moon?

If 2024 YR4 were to hit the moon, don’t expect a light show. “If it hits the moon, the impact wouldn’t be visible to the naked eye,” Farnocchia said. “You’d need a pretty big telescope, and even then, it might be hard to detect from Earth.”

However, skywatchers won’t have to wait long for something more dramatic. On April 13, 2029, the asteroid Apophis—about 1,100 feet wide—will fly closer to Earth than many satellites, putting on a rare and safe spectacle. “It’s going to be so close, and given its size, it’s going to be bright enough to be visible to the naked eye. It’s going to be as bright as the stars in the Little Dipper,” said Farnocchia.

NASA's Growing Ability to Predict Impacts

NASA has become increasingly adept at predicting asteroid impacts. “We had a few very small objects discovered before reaching Earth. They burn up harmlessly, but predicting their impacts and locations felt like a big accomplishment,” Farnocchia said.

New observation tools and modeling techniques are making it possible to predict not only impact locations but also recover fragments from impacts. “Recently, we were able to predict impact locations and recover meteorites, which is kind of interesting because that’s a final validation that you predicted the right impact point,” he said.

Why This Matters

While the moon isn’t in any real danger, 2024 YR4 has become a key case study for NASA’s planetary defense systems. It’s the first object since Apophis to climb to a 3 on the Torino Scale, and the first ever tracked with the James Webb Space Telescope, which improved impact projections by nearly 20%.

“There is so much I could say about YR4—it was really interesting to see the orbit behave exactly as we expected,” Farnocchia said. “I like to see how the predictions evolve with each new set of observations. It’s a sign that our models are working well.”

NASA expects YR4 to reenter view in 2028 for another round of observations—and possibly another plot twist.