Neptune's Moons and Rings Formed from Ancient Catastrophic Collision

• Caltech researchers have determined that Neptune's inner moons (Proteus, Larissa, Galatea) and rings likely originated from the destruction of larger primordial moons and a possible dwarf planet.
• Data from NASA’s James Webb Space Telescope (JWST) NIRSpec instrument reveals these objects lack water ice, contrary to typical outer solar system bodies.
• Evidence suggests a catastrophic event occurred when Neptune captured its largest moon, Triton, from the Kuiper Belt.

Scientific Findings

• Analysis of the NIRSpec data shows that Larissa, Galatea, and the rings contain water-rich clay minerals with magnesium, suggesting they were once deep interiors of larger bodies.
• Proteus does not contain these specific minerals, implying it formed from a different part of the debris disk created during the destruction of the original system.
• The material from these destroyed worlds eventually clumped together through accretion to form the current inner satellites and ring system.

Contextual Background

• Triton, Neptune's largest moon, comprises over 99.5 percent of the total mass of all 16 known Neptunian moons.
• Triton’s orbital characteristics and size support the hypothesis that it was captured by Neptune, causing severe disruption to the planet's original satellite environment.
• This study, published in Science Advances and led by Dr. Ryleigh Davis, provides new physical evidence of this past cataclysm, which may resemble the destruction of a system once similar to Uranus's current arrangement.