Neptune's inner moons may be icy relics from a cataclysmic past

New JWST data suggest Neptune’s inner moons Larissa, Galatea and Proteus may be fragments from ancient icy worlds shattered when Neptune captured Triton. Clay minerals—magnesium-rich phyllosilicates—were detected on Larissa and Galatea, potentially exposing material from deep interiors, while Proteus lacks these minerals. No water ice was detected, complicating the origin story. The researchers propose Triton’s capture turned former moons into rubble that reassembled as Neptune’s inner moons, or that a passing dwarf planet contributed debris. The findings, published July 29 in Science Advances, highlight Neptune’s violent past and the need for an ice-giant mission to study the planet further.