NASA’s James Webb Space Telescope has observed asteroid 2024 YR4, confirming it poses no significant threat to Earth in 2032 and beyond. The telescope used its Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) to measure the asteroid’s size, composition, and thermal properties.
Earlier this year, NASA reported that the risk of Earth impact from asteroid 2024 YR4 had been significantly lowered to near-zero by February. However, scientists wanted to study the asteroid further to gain insights into its characteristics and understand what asteroids of similar sizes are like.
Using NIRCam and MIRI, scientists measured the asteroid’s size directly and also obtained information on its reflectivity, which is related to its composition. This data will help inform the hazard posed by similar-sized asteroids in the future.
According to NASA’s Planetary Defense Coordination Office, the chance of 2024 YR4 hitting Earth has decreased significantly. However, scientists stress that these observations are still important for understanding the asteroid’s properties and improving detection methods.
The study revealed that the thermal properties of 2024 YR4 are different from those of larger asteroids, likely due to its fast spin rate and surface composition. The estimated size of the asteroid is approximately 60 meters (200 feet), roughly the height of a 15-story building.
The Webb observations contribute to our knowledge of near-Earth asteroids like 2024 YR4, which are studied by NASA’s planetary defense program and international scientists. By combining data from multiple telescopes, researchers have gained a better understanding of this asteroid’s properties and orbit, providing valuable insights for future asteroid detection and deflection efforts.
Source: https://blogs.nasa.gov/webb/2025/04/02/nasas-webb-finds-asteroid-2024-yr4-is-building-sized