SETI Live: What Happened to Neptune’s Moons?

New observations from JWST suggest that some of Neptune’s small inner moons may be the remnants of much larger icy worlds that were destroyed billions of years ago.

Using JWST, researchers studied Neptune’s rings and three of its inner moons - Larissa, Galatea, and Proteus - and discovered compositions unlike anything previously seen in the outer solar system. Larissa, Galatea, and the rings contain magnesium-rich clay minerals that form in the presence of liquid water, yet show no evidence of the water ice scientists expected to find.

Where did those minerals come from?

One possibility points to a dramatic event in Neptune’s past: the capture of Triton. Neptune’s largest moon likely formed elsewhere before being captured into its unusual retrograde orbit. That gravitational upheaval may have destroyed an earlier system of large icy moons, exposing material from deep within their interiors. Some of the debris could then have come back together to form the small moons and rings we see today.

Join SETI Live host Dr. Moiya McTier and lead author Dr. M. Ryleigh Davis of UC San Diego as they explore what JWST has revealed about Neptune’s strange moon system, Triton’s potentially destructive arrival, and how the remains of ancient worlds could offer a rare glimpse inside the icy bodies of the outer solar system.

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