The interstellar object, 3I/ATLAS, was first discovered in July 2025, and made its closest approach to the sun (perihelion) in late October. New observations of 3I/ATLAS were taken in December from the SPHEREx observatory—a near-infrared space observatory used for spectrophotometry. The analysis of these observations was recently discussed by a team of scientists in a paper on arXiv, and reveals some dramatic differences from the data taken before 3I/ATLAS reached perihelion.
