How many moons does Neptune have?
Neptune has 16 known moons. Fourteen of them are named after water deities and creatures from Greek mythology. The largest, Triton, accounts for nearly all the mass of the entire moon system.
Questions about Moons of Neptune
Short answers, pulled from the story.
Who discovered Triton and when?
William Lassell discovered Triton on the 10th of October 1846, just 17 days after Neptune itself was found. The name Triton was not in common use until at least the 1930s, having been suggested by Camille Flammarion in his 1880 book Astronomie Populaire.
Why is Triton unusual compared to other large moons?
Triton follows a retrograde orbit, moving against Neptune's direction of rotation, which indicates it was gravitationally captured rather than forming around Neptune. It is the largest captured moon in the Solar System; the next-largest suspected captured moon, Saturn's Phoebe, has only 0.03% of Triton's mass.
What happened to Neptune's original moons when Triton was captured?
Triton's highly eccentric initial orbit caused chaotic gravitational perturbations that sent Neptune's original inner moons into collisions, reducing them to a disc of rubble. The seven small inner moons visible today, including Proteus, re-accreted from that rubble after Triton's orbit eventually circularised.
What is special about Neptune's moon S/2021 N 1?
S/2021 N 1 has an orbital period of roughly 27 Earth years and orbits farther from its planet than any other known moon in the Solar System. It belongs to the Neso group, whose members have average orbital distances more than 125 times the Earth-Moon separation.
How was Hippocamp discovered as a moon of Neptune?
Mark R. Showalter discovered Hippocamp in 2013 by examining archival Hubble Space Telescope images of Neptune's ring arcs from 2009. He used a technique similar to panning to stack multiple exposures, then expanded his search area beyond the rings and found the moon, which he traced back through HST images to 2004.