Compounds of 3I/Atlas

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.