Psamathe , also known as Neptune X, is a

retrograde Retrograde may refer to: Film and television * Retrograde (2004 film), ''Retrograde'' (2004 film), a film by Christopher Kulikowski * Retrograde (2022 American film), ''Retrograde'' (2022 American film), a documentary film by Matthew Heineman * ...

irregular satellite In astronomy, an irregular moon, irregular satellite, or irregular natural satellite is a natural satellite following an orbit that is irregular in some of the following ways: Distant; inclined; highly elliptical; retrograde. They have often be ...

Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...

. It is named after

Psamathe Psamathe may refer to: Greek mythology * Psamathe (Nereid) * Psamathe (Crotopus), Daughter of Crotopus Other

* Psamathe (moon), moon of Neptune * Psamathe (polychaete), ''Psamathe'' (polychaete), polychaete worm genus * Psamathe (Leighton), '' ...

, one of the

Nereid In Greek mythology, the Nereids or Nereides ( ; ; , also Νημερτές) are sea nymphs (female spirits of sea waters), the 50 daughters of the ' Old Man of the Sea' Nereus and the Oceanid Doris, sisters to their brother Nerites. They ofte ...

s. Psamathe was discovered by Scott S. Sheppard and

David C. Jewitt David Clifford Jewitt (born 1958) is a British-American astronomer who studies the Solar System, especially its minor bodies. He is based at the University of California, Los Angeles, where he is a Member of the Institute for Geophysics and Pla ...

in 2003 using the 8.2 meter

Subaru Telescope is the telescope of the National Astronomical Observatory of Japan, located at the Mauna Kea Observatory on Hawaii. It is named after the open star cluster known in English as the Pleiades. It had the largest monolithic primary mirror in the ...

. Before it was officially named on February 3, 2007 (IAUC 8802), it was known by the

provisional designation Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calcu ...

S/2003 N 1. Psamathe VLT-FORS2 2010-07-13 annotated

Psamathe is about 38 kilometers in diameter. It orbits Neptune at a distance of between 25.7 and 67.7 million km (for comparison, the Sun– Mercury distance varies between 46 million and 69.8 million km) and requires almost 25 Earth years to make one orbit. The orbit of this satellite is close to the theoretical stable separation from Neptune for a body in a retrograde orbit. Given the similarity of Psamathe's orbital parameters with Neso (S/2002 N 4), it was suggested that both irregular satellites could have a common origin in the breakup of a larger moon. Both are farther from their primary than any other known moon in the Solar System.

References

External links

Neptune's Known Satellites
(by Scott S. Sheppard)
S/2003 N1 Neptune Satellite Movie Images
(image)

Mean orbital parameters (NASA)

{{Neptune Neso group Moons of Neptune Irregular satellites Discoveries by Scott S. Sheppard Astronomical objects discovered in 2003 Moons with a retrograde orbit

See also

References

External links