Traces of an ancient cosmic catastrophe discovered on Neptune's moons

Astronomers have discovered clay minerals on Neptune's inner moons that require liquid water to form—even though no water ice itself is present there. Scientists believe these are remnants of large icy bodies that were destroyed when Neptune captured its moon Triton. The study has been published in the journal Science Advances.

Clay minerals—phyllosilicates—were found by the James Webb telescope on the moons Larissa and Galatea. Previously, such minerals had never been detected in the outer part of the Solar System, beyond the orbit of Jupiter.

According to the researchers' estimates, only about 1% of the material remained in Neptune's system after the catastrophic event. The capture of the massive Triton could have torn apart the former satellite system and completely reorganized it.

"We were stunned to find these clays," admitted the lead author of the study, Riley DeVault, a researcher at the California Institute of Technology. According to her, all three studied moons contain the same hydrated mineral, which so far cannot be matched to anything in existing catalogs.

Neptune's inner moons, the authors note, are perhaps the only place in the Solar System where the interior composition of large icy bodies can be studied directly.