The destructive forces of shocking asteroids are estimated primarily by knowledge of their size. Near Earth Asteroid 2024 YR4 reached a peak 2032 impact probability on Earth at 3%, motivated the desire to determine its size. Due to its infrared capabilities, the NASA/ESA/CSA James Webbspace Telescope is uniquely suited to such evaluations. Johns Hopkins University astronomer Andrew Livkin and his colleagues used two Webb instruments to measure the diameter for 2024.
These web images show asteroid 2024 YR4 near Earth. Image credits: NASA/ESA/CSA/STSCI/A. RIVKIN, JHU/APL.
2024 yr4 On December 27, 2024, the Asteroid Terrestrial Impact of Río Hurtado was discovered by the Last Alert System (Atlas) station.
The asteroid took a close approach to Earth at a distance of 828,800 km (515,000 miles) two days before its discovery.
Initial observations from the 2024 YR4 showed that the diameter was 40-90 m (131-295 ft).
Dr. Eric McLennan, an astronomer at the University of Helsinki, said:
“However, thermal radiation at infrared wavelengths is a direct indicator of size.”
Dr. Livin, Dr. McLennan and his colleagues observed using the 2024 YR4 Webb’s Near-Infrared Camera (nircam) Mid-infrared instrument (Milli).
Nircam data reflects light, while Miri’s observations show heat light.
“The observations were taken to study the thermal properties of the 2024 YR4, including how quickly it heats and cools at the current distance from the sun, and how hot the heat is,” the astronomer said.
“These measurements show that this asteroid does not share the properties observed on the larger asteroid.”
“This could be a combination of its fast spin and a lack of fine sand on its surface.”
“More research is needed, but this is thought to coincide with surfaces dominated by rocks that are roughly below the size of a fist.”
New Webb observations show that the asteroid measures approximately 60 m (197 feet).
“The 2024 YR4 has been the smallest object that Webb has ever targeted and is one of the smallest objects that directly measure its size,” the researchers said.
“New observations from Webb provide unique information about the size of the YR4 in 2024, as well as complement the ground-based observations of the object’s location to improve understanding of the object’s trajectory and future trajectory.”
Team’s Survey results It was published in AAS research notes.
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As Livin et al. 2025. JWST observation of potentially dangerous asteroid 2024 YR4. res. Note AAS 9, 70; doi:10.3847/2515-5172/ADC6F0
Source: www.sci.news
