Triton (moon)
Triton is the largest moon of Neptune and the only large satellite in the Solar System with a retrograde orbit, indicating capture rather than in‑situ formation. Discovered on October 10, 1846 by William Lassell, Triton is an icy world with a thin nitrogen atmosphere, active geysers observed by Voyager 2 in 1989, and surface terrains suggesting ongoing cryovolcanic and tectonic processes.
