Nereid
From Conservapedia | Nereid | |
|---|---|
 Image of Nereid taken by Voyager 2 | |
| Date of discovery | May 1, 1949[1] |
| Name of discoverer | Gerard P. Kuiper[1][2] |
| Name origin | Any of fifty women, daughters of Nereus and Doris, who attended Neptune |
| Orbital characteristics | |
| Primary | Neptune |
| Order from primary | 8 |
| Periposeidion | 1,371,734 km[3] |
| Apoposeidion | 9,655,066 km[3] |
| Semi-major axis | 5,513,400 km[4] |
| Orbital eccentricity | 0.7512[4] |
| Sidereal month | 360.13619 da[4] |
| Avg. orbital speed | 1.12 km/s[5] |
| Inclination | 27.6°[5] to Neptune's equator |
| Rotational characteristics | |
| Sidereal day | 11.52 hr[6] |
| Rotational speed | 0.02576 km/s[3] |
| Physical characteristics | |
| Mass | 3.09 * 1019 kg[3] |
| Density | 1,500 kg/m³[7] |
| Mean radius | 170 km[7] |
| Surface gravity | 0.713 m/s²[3] |
| Escape speed | 0.156 km/s[3] |
| Surface area | 363,158 km²[3] |
| Composition | Ice and silicates[8] |
| Color | Neutral gray |
| Albedo | 0.155[7] |
Contents
Discovery and naming[edit]
Gerard P. Kuiper discovered Nereid in 1949. He gave it the generic name of the fifty female attendants of Neptune, the Roman god of the sea.
Orbital characteristics[edit]
Nereid is in a highly eccentric orbit around Neptune, and in fact its orbit is the most eccentric orbit of any solar system body.[9] Its sidereal month is about 360.14 Julian days. Nereid's orbit is inclined about 28 degrees from Neptune's equator, but is inclined only 7.23 degrees from the local Laplace plane.[4] Almost no astronomer believes that Nereid formed with the planet, and most astronomers believe that Nereid is a captured Kuiper belt or other trans-Neptunian object.[10]
Rotational characteristics[edit]
Nereid's sidereal day is 11.52 hours and is considered regular.[6]
Physical characteristics[edit]
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, Halimede (formerly S/2002 N 1), has the same neutral color, leading some astronomers to suggest that Halimede is a fragment of Nereid broken off in a collision with another, unknown object.[11]
Observation and Exploration[edit]
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[edit]
- ↑ 1.0 1.1 "Gazetteer of Planetary Nomenclature: Planetary Body Names and Discoverers." US Geological Survey, Jennifer Blue, ed. March 31, 2008. Accessed May 9, 2008.
- ↑ Kuiper, Gerard P. "The Second Satellite of Neptune." Publications of the Astronomical Society of the Pacific, 61:175-176, 1949. Accessed June 8, 2008.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Calculated
- ↑ 4.0 4.1 4.2 4.3 Neptunian Satellite Fact Sheet, NASA, January 22, 2008. Accessed May 9, 2008.
- ↑ 5.0 5.1 Hamilton, Calvin J. "Entry for Nereid." Views of the Solar System, 2000. Accessed June 8, 2008.
- ↑ 6.0 6.1 Grav, Tommy, Holman, Matthew J., and Kavelaars, J. J. "The Short Rotation Period of Neptune." Astrophysical Journal Letters 591:L71-L74, July 1, 2003. arXiv:astro-ph/0306001 doi:10.1086/377067 Accessed June 8, 2008.
- ↑ 7.0 7.1 7.2 "Planetary Satellite Physical Parameters." JPL, NASA. Retrieved June 8, 2008.
- ↑ "Nereid." Encyclopædia Britannica. 2008. Encyclopædia Britannica Online. 8 June 2008.
- ↑ Arnett, Bill. "Entry for Nereid." The
Nine8 Planets, May 6, 1995. Accessed June 8, 2008. - ↑ Tytell, David. "Neptune's Stowaway." Sky and Telescope, September 11, 2003. Accessed June 8, 2008.
- ↑ Grav, T., Holman M. J., and Fraser W. "Photometry of Irregular Satellites of Uranus and Neptune." Astrophys. J. 613(2004):L77-L80. arXiv:astro-ph/0405605v1 Accessed June 8, 2008.
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