James Webb Space Telescope reveals clay minerals on Neptune’s inner moons

NASA’s James Webb Space Telescope (JWST) has identified magnesium-rich clay minerals on Neptune’s inner moons, Larissa and Galatea. The discovery of these magnesium-rich phyllosilicates is significant because such minerals require liquid water and high temperatures to form, a chemical signature previously undetected in the outer solar system beyond Jupiter.

Researchers from a Caltech-led team observed that the moons and Neptune’s ring system lack the expected traces of water ice. This unexpected composition suggests that the moons may be the remnants of larger, ancient progenitor bodies that were destroyed.

The findings support the theory that Neptune’s original satellite system was catastrophically disrupted when the planet gravitationally captured its largest moon, Triton. The debris from this violent event likely coalesced to form the small, irregular inner moons observed today.