Article

NASA's SPHEREx mission observed interstellar comet 3I/ATLAS in December 2025, detecting organic molecules and a significant brightness increase post-perihelion. The observations revealed a diverse coma with carbon dioxide, water, and rocky materials, indicating active sublimation from subsurface ice. The comet, discovered in July 2025, is one of three known interstellar comets, and SPHEREx is expected to enhance understanding of cosmic origins.