“City Killer” Asteroid Discovered With Possible Earth Impact In 2032; Latest Tracking Increases Impact Risk

Asteroid 2024 YR4, a potential "city killer" asteroid has been discovered and early risk assessments have revealed a 1.9% chance that it could collide with Earth on December 22, 2032; raising concerns among scientists and planetary defense experts worldwide.

Discovery and Size of 2024 YR4

The asteroid was first discovered on December 27, 2024, by the El Sauce Observatory in Chile after a close approach to Earth on December 25th. 2024 YR4 was spotted during routine near-Earth object monitoring and quickly caught astronomers’ attention due to its size and potential trajectory.

Estimated to be between 130 and 300 feet (40 to 90 meters) wide, the asteroid is categorized as a “city killer,” capable of causing localized destruction on a catastrophic scale if it impacts Earth.

According to the European Space Agency (ESA), an asteroid of this size hits Earth once every few thousand years, making the discovery significant.

If 2024 YR4 were to strike, the explosion could unleash energy comparable to eight megatons of TNT—more than 500 times the power of the atomic bomb dropped on Hiroshima.

Planetary Defense Protocol Activated

The discovery of the asteroid has triggered the activation of two UN-endorsed global asteroid response teams.

The International Asteroid Warning Network has mobilized to conduct additional observations and refine estimates of the asteroid’s orbit.

On January 29, 2025, the International Asteroid Warning Network (IAWN) issued a public memo, placing 2024 YR4 at Level 3 out of 10 on the Torino Impact Hazard Scale, meaning it warrants close observation but does not yet pose an imminent threat.

Meanwhile, the Space Mission Planning Advisory Group has been notified and stands ready to recommend intervention strategies if necessary—potentially by deploying an intercepting spacecraft to deflect the asteroid, a method successfully tested in NASA’s DART mission.

The discovery was quickly flagged to planetary defense officials around the world, including Kelly Fast, acting planetary defense officer at NASA, who called it an object of serious interest.

“At this point, it’s ‘Let’s pay a lot of attention, let’s get as many assets as we can observing it." - Bruce Betts, Chief Scientist of The Planetary Society

Initial calculations show that 2024 YR4 follows a highly elliptical orbit that takes it around the inner planets, past Mars, and out toward Jupiter before swinging back. The asteroid is currently moving away from Earth and will not have another close pass until 2028, when astronomers hope to refine its trajectory further.

Potential Impact Zones and Damage

If 2024 YR4 were to hit Earth, the impact could flatten everything within a 50-kilometer (31-mile) radius—devastating any major city within its path.

Potential impact zones include a broad “risk corridor” stretching across the eastern Pacific Ocean, northern South America, the Atlantic Ocean, Africa, the Arabian Sea, and parts of South Asia.

The asteroid is expected to explode in the atmosphere, similar to the 1908 Tunguska Event, when an object between 100 and 150 feet wide detonated over Siberia, flattening 80 million trees across 770 square miles. Scientists believe the explosion of 2024 YR4 would occur high above the ground, creating a powerful shockwave that could decimate buildings and infrastructure over a wider area.

“If you put it over Paris, London, or New York, you basically wipe out the whole city and its surroundings,” - Bruce Betts, Chief Scientist of The Planetary Society

Planetary Defense Options

The good news is that the world has time to act. Planetary defense agencies have several potential methods to alter an asteroid’s course before impact, including kinetic impactors—spacecraft designed to crash into the asteroid and nudge it off its trajectory.

NASA successfully tested this technique in 2022 with its DART mission, which successfully altered the orbit of a small asteroid known as Dimorphos.

“I don’t see why it wouldn’t work...The bigger question is whether major nations would fund such a mission if their territory isn’t directly at risk.” - Andrew Rivkin, Planetary Astronomer at Johns Hopkins Applied Physics Laboratory and Lead Investigator for the DART mission

Other proposed strategies include using lasers to vaporize parts of the asteroid, creating a thrust effect that could push it off course, or deploying a gravity tractor—a large spacecraft that gradually tugs the asteroid using its gravitational pull.

If all else fails, the long warning time would allow authorities to evacuate potential impact zones and minimize casualties.

Monitoring the Asteroid

With Planetary Defense protocols in effect astronomers are closely tracking 2024 YR4 and gathering data to refine their predictions.

NASA’s Jet Propulsion Laboratory (JPL) and ESA’s Near-Earth Object Coordination Centre (NEOCC) have indicated that the asteroid will be observable through early 2025 before it becomes too faint to track. Its next observable approach won’t occur until 2028.

Over the coming months, scientists expect the impact probability to either increase or, more likely, drop as more data becomes available. Over the last 3 weeks the Asteroid impact risk has fluctuated up and down between 1.3% and 1.9% chance.

What Can The Public Do?

Despite the current risk estimate, experts urge the public not to panic.

Advances in tracking and planetary defense are why this asteroid was spotted with ample time to address it potential threat.

For now, scientists will continue monitoring 2024 YR4 to ensure it remains on their radar and, if necessary, activate mitigation strategies well before December 2032. With ongoing international collaboration, humanity may be more prepared than ever to face the dangers of the cosmos.