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Psamathe (moon)

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Psamathe
Discovery^[1]^[2]
Discovery images of Psamathe by the Subaru Telescope in 2003
Discovered by	Scott S. Sheppard David C. Jewitt J. Kleyna
Discovery date	19 August 2003
Designations
Designation	Neptune X
Pronunciation	/ˈsæməθiː/
Named after	Ψαμάθη Psamathē
Alternative names	S/2003 N 1
Adjectives	Psamathean /sæməˈθiːən/
Orbital characteristics
Epoch 1 January 2000 (Proper orbital element)
Observation arc	20.97 yr (7,660 days)^[3]
Mean anomaly	183.3° (proper)
Satellite of	Neptune
Group	Neso group
Proper orbital elements^[4]
Proper semi-major axis	47,615,100 km = 0.318 AU
Proper eccentricity	0.414
Proper inclination	127.8°
Proper mean motion	14.371255 deg / yr
Proper orbital period	25.05 yr (9149.514 d)
Precession of perihelion	874.6486 arcsec / yr
Precession of the ascending node	972.3189 arcsec / yr
Physical characteristics
Mean diameter	40 km (for albedo 0.04)^[5]
Albedo	0.04 (assumed)^[5]

Psamathe /ˈsæməθiː/, also known as Neptune X, is a retrograde irregular satellite of Neptune. It is named after Psamathe, one of the Nereids. Psamathe was discovered by Scott S. Sheppard and David C. Jewitt in 2003 using the 8.2 meter Subaru Telescope.^[5] Before it was officially named on February 3, 2007 (IAUC 8802), it was known by the provisional designation S/2003 N 1.^[6]

Animation of Psamathe moving in images by Very Large Telescope on 13 July 2010

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.^[5] Both are farther from their primary than any other known moon in the Solar System.^[7]

References[edit]

^ JPL (2011-07-21). "Planetary Satellite Discovery Circumstances". Jet Propulsion Laboratory. Retrieved 2011-10-24.

^ Green, Daniel W. E. (September 3, 2003). "Satellites of Neptune". IAU Circular. 8193. Retrieved 2011-10-24.

^ "Natural Satellites Ephemeris Service". Minor Planet Center. Retrieved 3 March 2024. Selection of Objects → "All Neptunian outer irregular satellites" → Check "I require Orbital Elements" → Get Information

^ Jacobson, R. A. (2008). "NEP078 - JPL satellite ephemeris". Planetary Satellite Mean Orbital Parameters. Retrieved 2009-09-23.

^ ^a ^b ^c ^d Sheppard, Scott S.; Jewitt, David C.; Kleyna, Jan (2006). "A Survey for "Normal" Irregular Satellites around Neptune: Limits to Completeness". The Astronomical Journal. 132 (1): 171–176. arXiv:astro-ph/0604552. Bibcode:2006AJ....132..171S. doi:10.1086/504799. S2CID 154011.

^ Marsden, Brian G. (2003). "MPEC 2003-R19 : S/2003 N 1". Minor Planet Center, Smithsonian Astrophysical Observatory. Retrieved 2011-01-08.

^ Schmude, Richard Jr. (2008). Uranus, Neptune, Pluto and How to Observe Them. Springer. p. 106. ISBN 978-0-387-76601-0.

External links[edit]

Wikimedia Commons has media related to Psamathe (moon).

Moons of Neptune

Listed in approximately increasing distance from Neptune

Regular (inner)

Irregular

Triton

Triton

Prograde

Retrograde

See also

v t e Natural satellites of the Solar System
Planetary satellitesof	Earth Mars Jupiter Saturn Uranus Neptune
Dwarf planet satellitesof	Orcus Pluto Haumea Quaoar Makemake Gonggong Eris
Minor-planet moons	Near-Earth Florence Didymos Dimorphos Moshup Squannit 1994 CC 2001 SN₂₆₃ Main belt Kalliope Linus Euphrosyne Daphne Peneius Eugenia Petit-Prince Sylvia Romulus Remus Minerva Aegis Gorgoneion Camilla Elektra Kleopatra Alexhelios Cleoselene Ida Dactyl Roxane Olympias Pulcova Balam Dinkinesh (Selam) Jupiter trojans Patroclus Menoetius Hektor Skamandrios Eurybates Queta TNOs Lempo Hiisi Paha 2002 UX₂₅ Sila–Nunam Salacia Actaea Varda Ilmarë Gǃkúnǁʼhòmdímà Gǃòʼé ǃHú 2013 FY₂₇
Ranked by size	Ganymede largest: 5268 km / 0.413 Earths Titan Callisto Io Moon Europa Triton Titania Rhea Oberon Iapetus Charon Umbriel Ariel Dione Tethys Dysnomia Enceladus Miranda Vanth Proteus Mimas Ilmarë Nereid Hiʻiaka Actaea Hyperion Phoebe ...
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