Larissa (moon)

Source: Wikipedia, the free encyclopedia.
Larissa
synchronous
zero
Albedo0.09[8][13]
Temperature~51 K mean (estimate)
21.5[13]

Larissa, also known as Neptune VII, is the fifth-closest

inner satellite of Neptune. It is named after Larissa, a lover of Poseidon (the Greek equivalent of the Roman god Neptune
).

Larissa is also the eponymous nymph of the city in Thessaly, Greece.

Discovery

Voyager 2 was the space probe that confirmed the existence of Larissa

Larissa was first discovered by

Harold J. Reitsema, William B. Hubbard, Larry A. Lebofsky and David J. Tholen, based on fortuitous ground-based stellar occultation observations[14] on May 24, 1981. It was given the temporary provisional designation S/1981 N 1 and its supposed existence was announced on May 29, 1981.[15] The moon was later recovered and confirmed to be the only object in its orbit during the Voyager 2 flyby in 1989[16] after which it received the additional designation S/1989 N 2 on August 2, 1989.[17] The announcement by Stephen P. Synnott spoke of "10 frames taken over 5 days", which gives a recovery date sometime before July 28. The name was given and then confirmed by the International Astronomical Union on September 16, 1991.[18]

Characteristics

Size comparison between Larissa (lower left), the Moon (upper left) and Earth
Morphographic map of Larissa, showing whatever unclear surface features that Voyager 2 was able to image during its flyby.[10]

Larissa is the fourth-largest satellite of Neptune. It is irregular (non-spherical) in shape and appears to be heavily cratered, with no sign of any geological modification. It is likely that Larissa, like the other satellites inward of Triton, is a rubble pile re-accreted from fragments of Neptune's original satellites, which were disrupted by perturbations from Triton soon after that moon's capture into a very eccentric initial orbit.[19]

Larissa's orbit is nearly circular and lies below Neptune's

planetary ring
.

Exploration

Side-by-side comparison of Larissa imaged by Voyager 2 and an enhanced version to the right

Larissa has only been visited once by Voyager 2.[20] The probe was able to get some photographs with details of Larissa, showing its cratered surface; unlike the other inner moons of Neptune that only appeared as dots or smudges.

Notes

  1. ^ A volume of (3.5±1.0)×106 km3 was obtained from a detailed shape model, assuming dimensions of 208 km × 192 km × 178 km.[10] The long and short dimensions were estimated based on a single image, with the medium dimension assumed as halfway between those values.[11] The volume has been scaled according to more recently obtained dimensions of 216 km × 204 km × 168 km based on two images.[8]
  2. ^ A density of 0.05–1.5 g/cm3 was calculated by approximating the volume as a sphere with a radius of 97±3 km.[12] The mass was calculated with the provided density and the assumed volume.
  3. ^ Density obtained from the calculated mass and the calculated volume.
  4. ^ Surface gravity derived from the mass m, the gravitational constant G and the radius r:
  5. ^ Escape velocity derived from the mass m, the gravitational constant G and the radius r:

References

  1. ^ "Larissa In Depth". solarsystem.nasa.gov/. Retrieved September 3, 2020.
  2. ^ "Larissa". Merriam-Webster.com Dictionary.
  3. ^ Boccaccio (1974). The book of Theseus.
  4. ^ Livy (1850 trans.) The history of Rome, v. 3
  5. ^ Bell (1790). Bell's New pantheon.
  6. ^ Jacobson, R. A.; Owen, W. M. Jr. (2004). "The orbits of the inner Neptunian satellites from Voyager, Earthbased, and Hubble Space Telescope observations". Astronomical Journal. 128 (3): 1412–1417.
    S2CID 121398325
    .
  7. PMID 30787452
    .
  8. ^ a b c d Karkoschka, Erich (2003). "Sizes, shapes, and albedos of the inner satellites of Neptune". Icarus. 162 (2): 400–407.
    doi:10.1016/S0019-1035(03)00002-2
    .
  9. ^ "Larissa In Depth". solarsystem.nasa.gov. Archived from the original on January 27, 2022. Retrieved September 3, 2020.
  10. ^ a b Stooke, Philip J. (1994). "The surfaces of Larissa and Proteus". Earth, Moon, and Planets. 65 (1): 31–54.
    S2CID 121825800
    .
  11. ISSN 0148-0227
    .
  12. ISSN 0019-1035
    .
  13. ^ a b "Planetary Satellite Physical Parameters".
    JPL
    (Solar System Dynamics). 2010-10-18. Retrieved 2011-10-11.
  14. ^ Reitsema, Harold J.; Hubbard, William B.; Lebofsky, Larry A.; Tholen, David J. (1982). "Occultation by a Possible Third Satellite of Neptune". Science. 215 (4530): 289–291.
    S2CID 21385195
    .
  15. ^ Marsden, Brian G. (May 29, 1981). "S/1981 N 1". IAU Circular. 3608. Retrieved 2011-10-26.
  16. ^ Smith, B. A.; Soderblom, L. A.; Banfield, D.; Barnet, C.; Basilevsky, A. T.; Beebe, R. F.; Bollinger, K.; Boyce, J. M.; Brahic, A. (1989). "Voyager 2 at Neptune: Imaging Science Results". Science. 246 (4936): 1422–1449.
    S2CID 45403579
    .     [on page 1435]
  17. ^ Marsden, Brian G. (August 2, 1989). "Satellites of Neptune". IAU Circular. 4824. Retrieved 2011-10-26.
  18. ^ Marsden, Brian G. (September 16, 1991). "Satellites of Saturn and Neptune". IAU Circular. 5347. Retrieved 2011-10-26.
  19. ^ Banfield, Don; Murray, Norm (October 1992). "A dynamical history of the inner Neptunian satellites". Icarus. 99 (2): 390–401.
    doi:10.1016/0019-1035(92)90155-Z
    .
  20. ^ "Larissa Facts". factsjustforkids.com. Retrieved September 3, 2020.


External links

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