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How is Triton’s interior thought to be arranged?

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Moons of Neptune: Triton — Triton Image of Triton, Neptune's largest satellite, captured by a camera aboard Voyager 2, 1989.

Triton’s interior is thought to be differentiated, consisting of a dense rocky core surrounded by a thick outer layer of predominantly water ice.1

This internal structure is believed to have resulted from the moon's history following its capture by Neptune. During the process of orbital circularization, Triton experienced intense tidal deformations that likely melted its entire interior. This molten state allowed for differentiation, where denser materials sank to form the core while more volatile materials rose toward the surface.1

As the moon subsequently cooled, the outer water-ice layer solidified. Scientists believe this layer later expanded as it froze, which caused the outer crust to fracture. These fractures, visible in images of the surface, provide evidence for the existence of this water-ice interior, as it is the primary candidate for a material that expands upon freezing.1