The James Webb Space Telescope will be used to better determine the size and orbit of asteroid 2024 YR4, whose risk of impact in 2032 is considered very low. The object, discovered in December 2024, currently has a 98% probability of passing close to Earth, although some uncertainty remains because it will soon become unobservable until 2028.
Although any potential impact would be local in scale due to the asteroid’s small size, the situation requires attention from the international planetary defence community. To properly assess the real hazard, knowing the orbit alone is not sufficient: accurately determining the object’s diameter is crucial. Current estimates range between 40 and 90 metres. This uncertainty arises from the fact that observations to date have been made only in visible light, whose interpretation depends on the asteroid’s reflectivity. Whether the object measures 40 or 90 metres is critical, as the consequences in each case would be very different.
