On February 20, 2025 (Hawaii-Aleutian Standard Time, HAST), the Subaru Telescope captured images of asteroid 2024 YR4, which will pass close to the Earth in 2032. The positional data obtained from these observations was used to refine the asteroid’s orbit, and assure us that the asteroid will not actually hit the Earth.
Discovered in December 2024, asteroid 2024 YR4 is estimated to be 40–90 meters in diameter. It follows a long elliptical orbit around the Sun with a period of approximately four years. For most of its orbit, it remains far from the Earth; however, when it approaches the Sun, it crosses Earth's orbit and occasionally comes close to the Earth. The International Asteroid Warning Network (IAWN)—coordinated by the United Nations Office for Outer Space Affairs—issued the first-ever official impact risk notification in history for 2024 YR4 because there was a slight possibility it could collide with the Earth in December 2032. Now global efforts are working to observe the asteroid with better precision to refine the estimates of its trajectory.
The Subaru Telescope observations of 2024 YR4 were conducted at the request of the JAXA Planetary Defense Team, responding to IAWN’s call for improved orbital tracking. On February 20, 2025 (HAST), Hyper Suprime-Cam (HSC), a wide-field prime-focus camera mounted on the Subaru Telescope, successfully imaged 2024 YR4 and precisely measured its position. The asteroid's brightness was also measured and found to be 24.3 magnitude in r-band (red visible light).
Dr. Tsuyoshi Terai of the Subaru Telescope, National Astronomical Observatory of Japan (NAOJ), who led the observations, comments: “Although 2024 YR4 appeared relatively bright at the time of its discovery, it has been steadily fading as it moves away from the Earth. By late February, observations would have been extremely challenging without a large telescope. This mission was successfully accomplished thanks to the Subaru Telescope’s powerful light-gathering capability and HSC’s high imaging performance.”
The observation results have been reported to the Minor Planet Center (MPC) of the International Astronomical Union, contributing to a more precise determination of 2024 YR4’s orbital elements. Based on new information, IAWN has revised its estimate of the asteroid colliding with the Earth in 2032, downgrading it to only a 0.004 percent chance of collision, much lower than the estimate at the beginning of February.
Source: Subaru Telescope/Topics
Related Link(s)
- Subaru Telescope Observes Near Earth Asteroid 2024 YR4 (Subaru Telescope)
- FINAL NOTIFICATION: NO SIGNFICANT POTENTIAL FOR FUTURE IMPACT WITH EARTH BY NEAR-EARTH ASTEROID 2024 YR4 (PDF) (IAWN)
