Changes

== Discovery and naming ==

== Discovery and naming ==

Gerard P. Kuiper discovered Nereid in 1949. He gave it the generic name of the fifty female attendants of Neptune, the [[Rome|Roman]] god of the sea.

Gerard P. Kuiper discovered Nereid in 1949. He gave it the generic name of the fifty female attendants of [[Neptune]], the [[Rome|Roman]] god of the sea.

== Orbital characteristics ==

== Orbital characteristics ==

Nereid is in a highly eccentric orbit around Neptune, and in fact its orbit is the most eccentric orbit of any [[solar system]] body.<ref name=Arnett>Arnett, Bill. "[http://www.nineplanets.org/nereid.html Entry for Nereid]." ''The <s>Nine</s> 8 Planets'', May 6, 1995. Accessed June 8, 2008.</ref> Its sidereal month is about 360.14 Julian days. Nereid is inclined about 28 degrees from Neptune's equator, but is inclined only 7.23 degrees from the local Laplace plane.<ref name=neptunesatfact/> Almost no astronomer believes that Nereid formed with the planet, and most astronomers believe that Neptune is a captured [[Kuiper belt]] or other [[Trans-Neptunian objects|trans-Neptunian object]].<ref name=Tytell>Tytell, David. "[http://www.skyandtelescope.com/news/3308056.html?page=1&c=y Neptune's Stowaway]." ''Sky and Telescope'', September 11, 2003. Accessed June 8, 2008.</ref>

Nereid is in a highly eccentric [[orbit]] around Neptune, and in fact its orbit is the most eccentric orbit of any [[solar system]] body.<ref name=Arnett>Arnett, Bill. "[http://www.nineplanets.org/nereid.html Entry for Nereid]." ''The <s>Nine</s> 8 Planets'', May 6, 1995. Accessed June 8, 2008.</ref> Its sidereal month is about 360.14 [[Julian]] days. Nereid is inclined about 28 [[degrees]] from Neptune's equator, but is inclined only 7.23 degrees from the local Laplace plane.<ref name=neptunesatfact/> Almost no astronomer believes that Nereid formed with the planet, and most astronomers believe that Neptune is a captured [[Kuiper belt]] or other [[Trans-Neptunian objects|trans-Neptunian object]].<ref name=Tytell>Tytell, David. "[http://www.skyandtelescope.com/news/3308056.html?page=1&c=y Neptune's Stowaway]." ''Sky and Telescope'', September 11, 2003. Accessed June 8, 2008.</ref>

== Rotational characteristics ==

== Rotational characteristics ==

Nereid's sidereal day is 11.52 hours and is considered regular.<ref name=Grav/>

Nereid's [[sidereal]] day is 11.52 hours and is considered regular.<ref name=Grav/>

== Physical characteristics ==

== Physical characteristics ==

Nereid has a mass of 3.09 * 10¹⁹ kg, the third greatest mass of the moons of Neptune. Its color is neutral-gray. Another moon of Neptune, [[Hallimede]] (formerly S/2002 N 1), has the same neutral color, leading some astronomers to suggest that Hallimede is a fragment of Nereid broken off in a collision with another, unknown object.<ref name=Grav2>Grav, T., Holman M. J., and Fraser W. "[http://arxiv.org/abs/astro-ph/0405605 Photometry of Irregular Satellites of Uranus and Neptune]." ''Astrophys. J.'' 613(2004):L77-L80. {{arXiv|astro-ph/0405605v1}} Accessed June 8, 2008.</ref>

Nereid has a [[mass]] of 3.09 * 10¹⁹ kg, the third greatest mass of the moons of Neptune. Its color is neutral-gray. Another moon of Neptune, [[Hallimede]] (formerly S/2002 N 1), has the same neutral color, leading some astronomers to suggest that Hallimede is a fragment of Nereid broken off in a collision with another, unknown object.<ref name=Grav2>Grav, T., Holman M. J., and Fraser W. "[http://arxiv.org/abs/astro-ph/0405605 Photometry of Irregular Satellites of Uranus and Neptune]." ''Astrophys. J.'' 613(2004):L77-L80. {{arXiv|astro-ph/0405605v1}} Accessed June 8, 2008.</ref>

== Observation and Exploration ==

== Observation and Exploration ==

Telescopic observation has revealed little about Nereid beyond its orbital elements. The one spacecraft that visited the Neptunian system, [[Voyager 2]], captured one low-resolution image of Nereid but did not fly close enough to it to discover more.

Telescopic observation has revealed little about Nereid beyond its orbital elements. The one [[spacecraft]] that visited the Neptunian system, [[Voyager 2]], captured one low-resolution image of Nereid but did not fly close enough to it to discover more.

== References ==

== References ==