Webb Finds Clay on 2 Neptune Moons, Bolstering Triton Capture Massacre Theory
Updated
Updated · Smithsonian Magazine · Aug 5
Webb Finds Clay on 2 Neptune Moons, Bolstering Triton Capture Massacre Theory
3 articles · Updated · Smithsonian Magazine · Aug 5
Summary
James Webb spectroscopy found magnesium-rich phyllosilicates in Neptune’s rings and on Larissa and Galatea, tying the material to an ancient destructive event rather than local formation.
Liquid water is required to make those clay minerals, but the small, cold moons show no water ice, leading researchers to conclude the material came from the deep interior of a much larger icy world.
Triton is the leading suspect: the retrograde moon was likely captured from the Kuiper Belt and then disrupted Neptune’s original moon system, with some debris later reassembled into today’s inner moons.
Proteus lacked the same mineral signature, suggesting it formed from a different part of the debris disk or that later heating erased the evidence.
Voyager 2 remains the only spacecraft to visit Neptune—back in 1989—leaving scientists to argue that a new Uranus-Neptune mission is needed to test the scenario.