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

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

The space telescope has the singular capability of seeing 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 gases and dust seen in the coma of 3I/ATLAS. The information gathered by SPHEREx helps scientists better understand what materials 3I/ATLAS contains and how the interstellar object’s pristine ices react to the Sun’s heating as the comet journeys 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 the spacecraft bus were built by BAE Systems. The science analysis of the SPHEREx data is being conducted by a team of scientists at 13 institutions across the U.S., and in South Korea and Taiwan, led by Principal Investigator Jamie Bock, based at Caltech with a joint JPL appointment, and by JPL Project Scientist Olivier Dore. Data is processed and archived at IPAC at Caltech in Pasadena, which manages JPL for NASA. The SPHEREx dataset is freely available to scientists and the public.

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