Astronomers are closely observing asteroid 2024 YR4, which presents a slight but significant chance of impacting Earth in 2032.
The newly discovered asteroid has an estimated 2% chance of collision, though scientists stress that additional observations may adjust its trajectory and potentially rule out the risk. The space rock, ranging from 40 to 90 meters (131 to 295 feet) in diameter, is about the size of a large building, according to Dr. Paul Chodas, director of NASA’s Center for Near-Earth Object Studies (CNEOS).
While much smaller than the 10-kilometre-wide asteroid that contributed to the extinction of the dinosaurs 66 million years ago, 2024 YR4 could still cause significant regional damage if it were to collide with Earth.
Tracking the Threat
The asteroid was first spotted on December 27 by the ATLAS telescope in Chile, which is part of NASA’s Near-Earth Object (NEO) detection program. Since its discovery, astronomers have been utilizing several observatories, including those in Hawaii, Chile, and New Mexico, to monitor its trajectory.
The asteroid’s size is estimated based on the sunlight it reflects, but the James Webb Space Telescope will soon offer a more precise measurement by detecting its heat. Webb’s upcoming observations in March and May will further refine predictions of the asteroid’s orbit.
“Hawaiʻi’s telescopes are vital tools for planetary defense,” said Doug Simons, director of the University of Hawaii’s Institute for Astronomy. “With our advanced technology and strategic location, we are able to detect, track, and analyze asteroids with great precision, giving scientists the crucial time needed to assess potential threats and plan responses.”
By April, 2024 YR4 will no longer be observable by ground-based telescopes. If astronomers have not ruled out an impact by then, the asteroid will remain on the risk list until it returns in June 2028, though scientists are confident it won’t pose a danger that year.
Estimating the Impact Risk
Determining the asteroid’s exact size is crucial for evaluating the potential consequences of a collision.
“If the asteroid is at the larger end of its size range, an impact could cause significant blast damage up to 50 kilometers (31 miles) from the impact site,” Chodas explained. “However, this remains unlikely.”
The potential for damage arises from the asteroid’s extremely high speed (approximately 17 kilometers per second, or 38,028 miles per hour) as it would enter Earth’s atmosphere.
Impacts of this magnitude occur roughly every few thousand years, according to the European Space Agency (ESA). The last major event occurred in 1908, when a 30-meter-wide asteroid exploded over Siberia, flattening 2,150 square kilometers (830 square miles) of forest. A smaller 20-meter-wide asteroid exploded over Chelyabinsk, Russia, in 2013, injuring over 1,000 people and causing widespread property damage.
“If the asteroid is approximately 50 meters in diameter, and is confirmed to be a rocky object, the effects would resemble those of the Tunguska impact,” stated the ESA. “If it’s larger, the effects could extend across several tens of kilometers.”
Ongoing Monitoring
Despite extensive efforts, detecting asteroids of 2024 YR4’s size remains challenging. Scientists estimate there are around 600,000 rocky objects of a similar size, yet only about 12,000—roughly 2%—have been identified.
“Smaller asteroids frequently enter Earth’s atmosphere, disintegrating into fireballs; fortunately, these don’t cause significant damage,” explained Larry Denneau, an astronomer at the University of Hawaii’s Institute for Astronomy. “Larger asteroids can cause much greater damage, though they hit Earth far less often. Many large objects remain undetected, which is why we continually monitor the sky to stay ahead of any potential threats.”
Researchers remain optimistic that further observations will either confirm 2024 YR4’s trajectory poses no danger or provide enough warning if action becomes necessary.
