Newly discovered asteroid now has a slightly higher risk of hitting Earth

An artist's impression shows a generic asteroid. Detecting the threat of near-Earth objects such as asteroids that could cause harm to our planet is a primary focus of NASA and other space organizations. (ESA/FILE via CNN Newsource)

A recently discovered asteroid that has captured the attention of the astronomy community now has a slightly increased risk of affecting Earth.

Named 2024 YR4, the asteroid has a 2.2 per cent chance of hitting our planet on December 22, 2032, according to the European Space Agency. The risk assessment has increased from a chance of 1.2 per cent over the last week due to new observations.

Astronomers expect the percentage to evolve as more observations are shared. If this asteroid follows the pattern of other near-Earth asteroids after their discovery, the chances of impact will rise and then fall, according to the agency. For example, the asteroid Apophis was once considered one of the most hazardous asteroids, with the potential to strike Earth after its discovery in 2004. In 2021, scientists revised that opinion after a precise analysis of the asteroid’s orbit.

The more astronomers can observe asteroid 2024 YR4, the more they can refine their understanding of its size and trajectory, which will determine the likelihood of an impact.

“Basically, the more observations we get, the more we can localise and confirm the asteroid’s trajectory, which is most likely to turn out to be a flyby, and not an impact,” according to a blog post the agency shared. “Hence, we expect the risk forecast can be steadily/stepwise reduced to zero.”

The asteroid is estimated to be 131 to 295 feet (40 and 90 metres) wide.

The space rock has a “size range comparable to that of a large building,” said Dr. Paul Chodas, manager for the Center for Near Earth Object Studies, or CNEOS, at NASA’s Jet Propulsion Laboratory in Pasadena, California. Chodas added that the size of the asteroid, which astronomers are trying to determine with follow-up observations using multiple telescopes, is currently highly uncertain.

“If the asteroid turns out to be on the large end of its estimated size range, the impact could produce blast damage as far as 50 kilometres (31 miles) from the impact site,” Chodas said. “But that’s in the unlikely event that it might impact at all. The potential for damage arises because of the incredibly high speed (about 17 kilometres per second, or 38,028 miles per hour) at which the asteroid would enter the atmosphere.”

Asteroids of this size have an impact on Earth every few thousand years, and they can cause severe damage to local regions, according to the ESA.

In 1908, a 30-metre-wide (98-foot-wide) asteroid struck the Podkamennaya Tunguska River in a remote Siberian forest of Russia, according to the Planetary Society. The event leveled trees and destroyed forests across 830 square miles (2,150 square kilometres).

And in 2013, a 20-metre-wide (66-foot-wide) asteroid entered Earth’s atmosphere over Chelyabinsk, Russia. It exploded in the air, releasing 20 to 30 times more energy than that of the first atomic bomb, generating brightness greater than the sun, exuding heat, damaging more than 7,000 buildings and injuring more than 1,000 people.

Spotting an asteroid that’s new to science

The Asteroid Terrestrial-impact Last Alert System, or ATLAS, telescope in Rio Hurtado, Chile, first spied 2024 YR4 on December 27. The telescope is one of the asteroid discovery programs funded by NASA to scan the sky in search of near-Earth asteroids, said Davide Farnocchia, navigation engineer at JPL and CNEOS, via email.

Automated asteroid warning systems sent out an alarm after determining the asteroid had a slim chance of affecting Earth in 2032, bumping it to the top of the ESA’s asteroid risk list and NASA’s automated Sentry risk list on Dec. 31. Such lists include any known asteroids with a nonzero probability of colliding with Earth.

Since early January, astronomers have used the Magdalena Ridge Observatory in New Mexico, the Danish Telescope and the Very Large Telescope in Chile to track the asteroid, which is currently more than 28 million miles (45 million kilometres) from Earth and moving farther away over time, Farnocchia said.

As the asteroid moves away from Earth and becomes fainter, researchers will have to rely on larger telescopes to observe it. The celestial object should be visible through early April and disappear as it continues on its orbit around the sun. It won’t return to Earth’s vicinity until 2028, Farnocchia said.

If 2024 YR4 disappears from view before space agencies can entirely rule out any chance of impact, the space rock will remain on the risk list until it’s back in view in June 2028.

“Using the available tracking data, we can predict the future position of an asteroid,” Farnocchia said. “The longer we track an asteroid, the more precise the prediction. As we collect additional data, the uncertainty in the position of 2024 YR4 in 2032 will decrease.”

NASA and the ESA regularly track thousands of near-Earth asteroids, but depending on the size, the space rocks are not always easy to spot. But improvements in asteroid survey technology, and future asteroid-spotting missions, could detect objects astronomers haven’t been able to see in the past. Currently, there are no other known large asteroids that have more than a one per cent chance of affecting Earth, according to NASA.

Tracking a potential threat

Two international asteroid response groups endorsed by the United Nations — the International Asteroid Warning Network, chaired by NASA, and the Space Mission Planning Advisory Group, chaired by ESA — have been activated in response to the threat level.

The International Asteroid Warning Network is responsible for coordinating the organizations involved in tracking and characterizing the details of the asteroid — and if necessary, developing strategies to assess the consequences of an impact.

Meanwhile, the Space Mission Planning Advisory Group, which recently convened in Vienna, Austria, will provide recommendations and evaluate options for how to mitigate a potential impact if the asteroid remains a threat. Possible mitigation tactics include deflecting the asteroid in space, like NASA’s demonstration of the Double Asteroid Redirection Test in 2022, or evacuating potentially affected regions on the ground, Farnocchia said.

The group is continuing to monitor 2024 YR4 and will meet again in late April or early May as the space rock disappears from view to reassess whether any recommendations need to be made, according to the ESA.

“If 2024 YR4 remained a threat at the end of the current observing window, mitigation measures might be considered,” Farnocchia said. “But talk of mitigation is premature. The priority right now is to keep observing 2024 YR4 and reduce its positional uncertainties in 2032, since this is likely to rule out the impact.”

Ashley Strickland, CNN