Pluto and the largest moon of Neptune might be siblings

Neptune’s largest moon, Triton, and the dwarf planet Pluto may have shared a common origin before being separated in the early solar system, an analysis of their composition suggests.

Triton and Pluto have both been visited once by spacecraft, the former by NASA’s passing Voyager 2 in 1989 and the latter by NASA’s New Horizons probe in 2015. Both are icy bodies smaller than Earth’s moon with similar densities that appear to have hosted subsurface oceans at some point…