NASA’s SPHEREx Examines Comet 3I/ATLAS’s Coma

These observations from NASA’s SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer) show infrared light emitted by dust, water, organic molecules and carbon dioxide contained in the coma of comet 3I/ATLAS. The comet brightened significantly during the December 2025 period when SPHEREx made the observations, about two months after the icy body passed its closest distance from the Sun in late October.

The space telescope has the unique ability to view the sky in 102 colors, each representing a wavelength of infrared light that provides unique information about galaxies, stars, planet-forming regions or other cosmic features, including the various gas and dust observed in the 3I/ATLAS coma. The information collected by SPHEREx helps scientists better understand what materials 3I/ATLAS contains and how the interstellar object’s pristine ices respond to the Sun’s warming as the comet passes through the solar system.

The mission is managed by NASA’s Jet Propulsion Laboratory in Southern California for the agency’s Astrophysics Division within the Science Mission Directorate in Washington. The telescope and space bus were built by BAE Systems. The scientific analysis of the SPHEREx data is being conducted by a team of scientists from 13 institutions in the United States, South Korea, and Taiwan, led by principal investigator Jamie Bock, based at Caltech with a joint appointment at JPL, and by JPL project scientist Olivier Dore. The data is processed and archived at Caltech’s IPAC in Pasadena, which manages JPL for NASA. The SPHEREx dataset is freely available to scientists and the public.

For more information on the SPHEREx mission, visit: https://science.nasa.gov/mission/spherex/