Astronomy:Pandora (moon)

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Short description: Moon of Saturn
Pandora
PIA21055 - Pandora Up Close.jpg
View of Pandora's western hemisphere.[lower-alpha 1]
Discovery
Discovered byStewart A. Collins
D. Carlson
Voyager 1
Discovery dateOctober, 1980
Designations
Designation
Saturn XVII
Pronunciation/pænˈdɔːrə/
Named afterΠανδώρα Pandōra
AdjectivesPandoran[1]
Orbital characteristics[2]
Epoch December 31, 2003 (JD 2453005.5)
141720±10 km
Eccentricity0.0042
Orbital period0.628504213 d
Inclination0.050°±0.004° to Saturn's equator
Satellite ofSaturn
GroupPossible outer shepherd moon of the F Ring
Physical characteristics
Dimensions103.0 × 79.0 × 63.0 km
(± 0.6 × 0.6 × 0.4 km)[3](p2)
Mean diameter80.0±0.6 km[3](p2)
Volume268990±860 km3[4](p4)
Mass(1.357±0.002)×1017 kg[lower-alpha 2]
Mean density0.5045±0.0017 g/cm3[4](p4)
0.0022–0.0061 m/s2[3](p3)
0.019 km/s at longest axis
to 0.024 km/s at poles
Rotation periodsynchronous
Axial tiltzero
Albedo0.6
Physics≈ 78 K


Pandora is an inner satellite of Saturn. It was discovered in 1980 from photos taken by the Voyager 1 probe, and was provisionally designated S/1980 S 26.[5] In late 1985 it was officially named after Pandora from Greek mythology.[6] It is also designated Saturn XVII.[7]

Pandora was thought to be an outer shepherd satellite of the F Ring. However, recent studies indicate that it does not play such a role, and that only Prometheus, the inner shepherd, contributes to the confinement of the narrow ring.[8][9] It is more heavily cratered than nearby Prometheus, and has at least two large craters 30 kilometres (19 mi) in diameter. The majority of craters on Pandora are shallow as a result of being filled with debris. Ridges and grooves are also present on moon's surface.[10]

The orbit of Pandora appears to be chaotic, as a consequence of a series of four 118:121 mean-motion resonances with Prometheus.[11] The most appreciable changes in their orbits occur approximately every 6.2 years,[2] when the periapsis of Pandora lines up with the apoapsis of Prometheus and the moons approach to within about 1,400 kilometres (870 mi). Pandora also has a 3:2 mean-motion resonance with Mimas.[2]

From its very low density and relatively high albedo, it seems likely that Pandora is a very porous icy body. There is much uncertainty in these values, however, so this remains to be confirmed.

Gallery

References

Notes

  1. This view was taken by Cassini, during the spacecraft's close flyby on December 18, 2016. The image was taken from a distance of 40,500 kilometres (25,200 miles); the closest approach by the spacecraft during its 14-year tenure in the Saturn system.
  2. Calculated from the standard gravitational parameter GM = (9.058±0.011)×10−3 km3·s–2 given by Lainey et al. (2023), divided by the gravitational constant G = 6.6743×10−2 km3·kg–1·s–2.[4]

Citations

  1. Robert Kolvoord (1990) Saturn's F ring: imaging and simulation, p. 104
  2. 2.0 2.1 2.2 Spitale Jacobson et al. 2006.
  3. 3.0 3.1 3.2 Thomas & Helfenstein 2020.
  4. 4.0 4.1 4.2 Lainey et al. 2023.
  5. IAUC 3532.
  6. IAUC 4157.
  7. USGS: Planet and Satellite Names and Discoverers.
  8. "On the masses and motions of mini-moons: Pandora's not a "shepherd," but Prometheus still is". Planetary Society. 2014-07-05. http://www.planetary.org/blogs/emily-lakdawalla/2014/07010001-ringmoons-shepherds.html. 
  9. Cuzzi, J. N.; Whizin, A. D.; Hogan, R. C.; Dobrovolskis, A. R.; Dones, L.; Showalter, M. R.; Colwell, J. E.; Scargle, J. D. (April 2014). "Saturn's F Ring core: Calm in the midst of chaos". Icarus 232: 157–175. doi:10.1016/j.icarus.2013.12.027. ISSN 0019-1035. Bibcode2014Icar..232..157C. 
  10. Solar System, NASA: Pandora.
  11. Renner et al. 2005.

Sources

External links

  • Pandora at NASA's Solar System Exploration
  • Pandora at The Planetary Society