Why asteroid 2024 YR4 is unlikely to hit Earth in 2032 and how scientists keep track

NASA and the European Space Agency's Webb Space Telescope will observe this near-Earth asteroid in March before the object disappears from view. Once that happens, scientists will have to wait until 2028 when it passes our way again.

What's an asteroid?

Asteroids are space rocks orbiting the sun that are considerably smaller than planets. Scientists believe they're the leftovers from the solar system's formation 4.6 billion years ago.

There are so many asteroids orbiting between Mars and Jupiter — millions of them — that this region is known as the main asteroid belt. They sometimes get pushed out of the belt and can end up all over the place — like this one.

How do scientists track potentially dangerous asteroids?

A telescope in Chile discovered the asteroid 2024 YR4 in December. It's estimated to be 130 feet to 300 feet (40 meters to 90 meters) across. Observations by the Webb telescope should provide a more precise measurement, according to NASA.

NASA and the European Space Agency initially put the odds of a strike at just over 1%. By Thursday, it had risen to roughly 2%. NASA describes that as still "extremely low."

Until scientists have a better understanding of the asteroid's path around the sun, they caution the odds will continue to fluctuate — and quite possibly fall to zero.

"You don't have to be worried about anything. It's a curiosity," said Larry Denneau, senior software engineer with the University of Hawaii's asteroid impact alert system that first spotted the asteroid. "Don't panic. Let the process play out, and we'll have a for-sure answer."

In 2021, NASA gave the all-clear to another potentially worrisome asteroid, Apophis, after new telescope observations ruled out any chance of it hitting Earth in 2068.

Should we worry about asteroid 2024 YR4?

It's way too soon to fret over this asteroid, according to the experts.

"No one should be concerned that the impact probability is rising. This is the behavior our team expected," Paul Chodas, director of NASA's Center for Near-Earth Object Studies, said in an email. "To be clear, we expect the impact probability to drop to zero at some point."

Since the asteroid's size and orbit are uncertain, it's unclear where it might hit and what the possible impacts would be should it strike Earth. If the asteroid is on the smaller end, ESA said any potential impacts would be local similar to the Tunguska event that flattened thousands of square miles of forest in remote Siberia in 1908. But if it's close to 330 feet (100 meters), "the consequences would be significantly worse."

Chodas said once Webb pinpoints the asteroid's size, NASA can predict "how serious an impact this asteroid could produce and how difficult a task it might be to deflect this asteroid."

NASA already has some experience nudging an asteroid. The space agency's Dart spacecraft deliberately rammed a harmless asteroid in 2022 in the first planetary defense test of its kind, altering its orbit around its larger companion asteroid.