James Webb Telescope Investigates ‘City-Killer’ Asteroid 2024 YR4 Before Its 2032 Close Encounter

The James Webb Space Telescope (JWST) has completed its first look at the asteroid 2024 YR4, a rock that has raised eyebrows due to its close approach to Earth and the moon in December 2032. The worldwide team of astronomers received some emergency time with JWST in February, allowing them this critical observation.

Initial studies showed that 2024 YR4 might be bigger and rockier than experts thought. Fortunately, JWST confirmed what NASA had already discovered: there is no danger of the asteroid hitting Earth in 2032. However, a collision with the moon is still possible. The researchers noted, “While an Earth impact has been ruled out, the moon remains at risk,” according to their preliminary report.

Astronomers initially found 2024 YR4 in December 2024. Early estimates measured it to be about 180 feet (55 meters) across, similar in height to the Leaning Tower of Pisa. Its path crosses Earth’s orbit, making it a potential threat. If it were to collide with our planet, the consequences could be catastrophic, equivalent to 500 Hiroshima bombs.

Earlier calculations put its chance of impacting Earth at about 3.1%—the highest ever recorded for an asteroid of this size. Luckily, NASA later adjusted that probability down to zero. The European Space Agency (ESA) also mobilized JWST’s emergency time for a closer study of this potentially hazardous asteroid.

JWST’s infrared sensors are key for understanding 2024 YR4 better. Unlike ground-based telescopes, which only capture sunlight reflecting off the asteroid, JWST can measure its heat. “The brightness can vary significantly based on how reflective the surface is,” ESA explained. Thus, the earlier estimates of the asteroid’s size could be misleading without this infrared data.

During JWST’s first observation, the asteroid was monitored over a five-hour period, revealing it is likely about 200 feet (60 meters) in diameter. Surprisingly, it’s also cooler than expected, indicating it may be rockier than previous studies assumed.

Even though 2024 YR4 poses no immediate threat to Earth, there’s still about a 2% chance it could hit the moon in 2032. This possibility, while worrying, also sparks excitement among scientists. Astronomer Andrew Rivkin from Johns Hopkins University noted, “The moon gets hit by tiny meteors all the time, but seeing a known asteroid strike could give us unique insights into lunar geology.”

Alan Fitzsimmons, a professor at Queen’s University Belfast, shared his hope for a moon impact, emphasizing its unique research potential. “Studying the impact would let us observe how a moon crater forms from a known object, which we’ve never had the chance to do before.”

As scientists continue to refine 2024 YR4’s trajectory and monitor its path with a second JWST observation planned for May 2025, the excitement around this event grows. The opportunity to witness a direct hit on the moon by an identifiable asteroid would be a historic moment in space research.

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