Psamathe is so distant from Neptune it takes almost 26 Earth years to make a single orbit around the ice giant. The moon's orbit is among the most distant from its planet than any other known moon in our solar system.
The small moon shares similar orbital parameters with with another moon of Neptune -- Neso. Both Psamathe and Neso may be fragments from the break-up of a larger moon billions of years ago.
Psamathe was discovered by Scott S. Sheppard, David C. Jewitt and Jan T. Kleyna 29 August 2003 using the 8.3-m Subaru reflector at the Mauna Kea Observatory on the island of Hawaii.
How Psamathe Got its Name:
Moons of Neptune are named for characters from Greek or Roman mythology associated with Neptune or Poseidon, or the oceans. Irregular satellites are named for the Nereids, daughters of Nereus and Doris and the attendants of Neptune.
Psamathe like many of the satellites of Neptune, is named after one of the Nereids. Psamathe was originally designated S/2003 N 1.