Will Asteroid 2024 YR4 Hit Earth? Scientists Assess 2032 Impact Risk
SANTA BARBARA, Calif. — Science enthusiasts are closely watching asteroid 2024 YR4, the most hazardous asteroid ever detected.
Westmont College physics professor emeritus Ken Kihlstrom said the asteroid's name includes the year it was discovered.
On Tuesday, NASA calculated a 3.1% chance that the space rock could collide with Earth in 2032, while the European Space Agency’s risk assessment placed the probability at 2.8%.
The slight difference in calculations is due to the agencies using different tools to determine the asteroid’s orbit and model its potential impact. However, both percentages exceed the 2.7% chance once associated with Apophis, an asteroid discovered in 2004. This makes 2024 YR4 the most significant asteroid discovery in the past two decades.
The asteroid currently ranks 3 on the Torino Impact Hazard Scale, which categorizes potential asteroid collisions with Earth. It is estimated to be between 131 and 295 feet (40 and 90 meters) wide, roughly the size of a large building.
“That is a decent size, but it is not even as large as the objects NASA has been tasked with finding—those 140 meters and larger,” said Kelly Fast of NASA. “We want to find all of them that could pose a future impact threat.”
Despite its ranking, Kihlstrom believes the likelihood of impact is low.
“They are trying to map its orbit, and with near-Earth asteroids, the question is whether there is a chance of impacting the Earth,” Kihlstrom said. “This one has a slight chance. It’s like taping a penny to an archery target and shooting from 50 feet away—what are the odds of hitting that penny? Maybe 3 or 4%, so it’s unlikely.”
Even if 2024 YR4 were to collide with Earth, Kihlstrom noted that 70% of the planet is covered in ocean, making it most likely to land in water.
“If it lands on land, most of that is unpopulated, so the odds of hitting a populated area are slim,” he added.
Scientists could also attempt to alter the asteroid’s trajectory.
“Is there a way to divert an asteroid? There was a test, like the DART mission, where they successfully changed an asteroid’s path,” Kihlstrom said. “But to be effective, you really want to do it when the asteroid is very far away because even a small change in trajectory early on leads to a huge change over time.”
University of Nevada, Las Vegas, physics professor Michael Pravica said conclusions may be premature.
“I think asteroids come and go. They have been around for billions of years. I think right now we need to get more data, and then we can draw a better conclusion about what to do in 2032.”
Pravica added that he believes there are more pressing issues, such as climate change, recent fires in Southern California, and geopolitical concerns, including the threat of nuclear war.
Students at Westmont College are drawn to the Westmont Observatory, where they can learn about astronomy.
Some students heard about the asteroid on TikTok, while others were unaware of it but seemed interested in learning more.
Astronomers are using multiple telescopes to study the asteroid’s size and orbit, and further observations will likely lower the projected 2032 impact probability.
