Overview
- NASA’s SPHEREx recorded a major brightness spike from 3I/ATLAS in December 2025, about two months after its closest approach to the sun.
- Spectral data cataloged organic molecules including cyanide, methane, and methanol during the post-perihelion outgassing.
- Researchers attribute the delayed activity to solar heat reaching deep ices beneath a radiation-processed crust, with findings reported in a preliminary research note.
- ESA repurposed its Jupiter-bound Juice spacecraft to observe the comet at perihelion, activating five instruments and using its high-gain antenna as a sunshield, with data still returning.
- Trajectory analyses confirm the comet is unbound to the sun and suggest a possible thick-disk origin, as it departs the solar system with a potential final look by Juno near Jupiter.