Larissa (moon)
Encyclopedia : L : LA : LAR : Larissa (moon)
- Larissa is also an asteroid, 1162 Larissa, and there is also the paronymous asteroid 302 Clarissa.
Larissa (lə-ris'-ə, IPA /ləˈrɪsə/, Greek Λάρῑσα), or Neptune VII, is the fifth closest of Neptune's known moons. It is named after Larissa, a lover of Poseidon (Neptune) in Greek mythology.
It was first discovered by Harold J. Reitsema, William B. Hubbard, Larry A. Lebofsky and David J. Tholen based on ground-based stellar occultation observations on May 24, 1981, and given the temporary designation S/1981 N 1. The announcement was made on January 15, 1982 (Science, vol. 215, pp. 289-291). The moon was not recovered until the Voyager 2 flyby in 1989 when it received the designation S/1989 N 2. Stephen P. Synnott announced (IAUC 4824) its recovery on August 2, 1989, speaking only of “10 frames taken over 5 days”, which gives a discovery date of sometime before July 28.
Larissa is irregular (non-spherical) in shape and appears to be heavily cratered, with no sign of any geological modification. Little else is known about it. Since the Larissean orbit is below Neptune's synchronous orbit radius it is slowly decaying due to tidal forces and will one day break up into a planetary ring or enter Neptune's atmosphere.
- Orbital radius: 73,548 km
- Diameter: 216×204×168 km
- Estimated Mass: ~4.9×1018 kg
- Estimated density: ~1.3 g/cm3
- Orbital period: 0.555 days
- Orbital inclination: 0.242° (to Neptune's equator), 0.205° (to the local Laplace plane), 28.63° (to the ecliptic)
External links
- [IAU Circular 3608 describing the discovery of S/1981 N 1]
- [IAU Circular 4824 describing the discovery of S/1989 N 2, 3, and 4]
- [The Nine Planets: Larissa]
- [Views of the Solar System: Larissa]
References
| Neptune (satellites) [http://encycl.opentopia.com/ edit ] |
|---|
| Naiad | Thalassa | Despina | Galatea | Larissa | Proteus | Triton | Nereid |
| S/2002 N 1 | S/2002 N 2 | S/2002 N 3 | Psamathe | S/2002 N 4 |
| See also: | Neptune-Sun Lagrangian point asteroids | Rings of Neptune |
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