Asteroid 2024 YR4 No Longer Threatens Earth, But Moon in Sites

Late last year, a newly discovered asteroid caused quite a stir when initial observations revealed a greater than 1% chance that it would strike the Earth in 2032. The medium-sized asteroid, dubbed 2024 YR4, makes a close approach with the Earth approximately every four years, and each time there’s an opportunity for impact. Astronomers knew it would make a clean pass in 2028, but where it would end up four years later was less clear.

For a moment, it looked like we might be in store for a cosmic fight akin to Asteroid vs Earth (streaming now on Peacock). Since then, additional observations, including some new pictures from the James Webb Space Telescope (JWST), more clearly defined its actual orbit and determined there is essentially zero chance 2024 YR4 will impact the Earth in the foreseeable future.

However, at least some of its potential paths still intersect the Moon, which means we might be witness to an incredible lunar asteroid strike early next decade.

To be clear, the asteroid will either strike the Moon or it won’t. The ball (asteroid) is already in motion and it will go where it goes. The uncertainty comes from a lack of data. Asteroids are hard to see, tiny distant ones doubly so, and it’s hard to figure out precisely how they’re moving through space without a lot of observation time.

There are a lot of factors at play including the precise speed and direction of an asteroid’s current orbit, what other large objects (like the Earth) might influence its orbit, and how sunlight reacts with surface materials. All of these factors and more can influence how an asteroid moves through space and where it ends up.

When an asteroid is discovered, astronomers calculate all of its potential paths and determine how many of them intersect the Earth or, in this case, the Moon. If, for instance, there were 100 possible paths and one of them intersected the Earth, there would be a 1% chance of impact. In the months following 2024 YR4’s discovery, there was a moment when the probability of impacting the Earth got above 3%. During that period, 2024 YR4 held the dubious honor of being the most dangerous rock in near-Earth space.

JWST snaps photos of asteroid that might strike the Moon

On March 8, astronomers pointed JWST, humanity’s most powerful space-based observatory, toward the asteroid 2024 YR4. Visible reflected sunlight was captured by the telescope’s Near-Infrared Camera (NIRCam) while thermal light (heat) was gathered by the onboard Mid-Infrared Instrument (MIRI).

The combined data revealed the asteroid as an ill-defined speck in deep space. The observations, while fuzzy, showcase the smallest object ever observed by JWST (which usually looks at vast galaxies at the edges of the observable universe). They also confirm that the asteroid is about 200 feet across, spinning rapidly, and has a surface made of roughly fist-sized rocks.

While the Earth is no longer at risk from this particular impactor, there is still a statistically significant chance it will strike the Moon. Additionally, astronomers say that these observations helped us to better understand how this type of space rock operates and served as a test run for any other potentially dangerous near-Earth objects coming down the pipe.

NASA’s Center for Near Earth Object Studies (CNEOS) at JPL updated the asteroid’s lunar impact probability to 3.8%, based on the new JWST data and ongoing ground-based observations. If 2024 YR4 hits the Moon in 2032, it won’t change the Moon’s orbit or otherwise cause any long-term problems, but it could be one hell of a show.

In the meantime, catch Asteroid vs Earth, streaming now on Peacock.