Calypso (moon)

Calypso
	Calypso image from Cassini ; (February 13, 2010)
Discovery
Discovered by	Dan Pascu; P. Kenneth Seidelmann; William A. Baum; Douglas G. Currie;
Discovery date	March 13, 1980
Designations
Designation	Saturn XIV
Pronunciation	/kəˈlɪpsoʊ/
Named after	Καλυψώ Kalypsō
Alternative names	Tethys C; S/1980 S 25
Adjectives	Calypsoan /kælɪpˈsoʊ.ən/, Calypsonian /kælɪpˈsoʊniən/
Orbital characteristics
Semi-major axis	295000 km
Eccentricity	0.001
Orbital period (sidereal)	1.887803 d
Inclination	1.56° (to Saturn's equator)
Satellite of	Saturn
Group	L5 Tethys trojan
Physical characteristics
Dimensions	29.4 × 18.6 × 12.8 km; (± 0.6 × 1.8 × 0.6 km)
Mean diameter	19.0±0.8 km
Volume	3591 km3
Mass	≈ 2×1015 kg (assumed; unmeasured)
Mean density	≈ 0.5 g/cm3 (assumed; unmeasured)
Surface gravity	≈ 0.0009–0.0013 m/s2
Escape velocity	≈ 0.004 km/s at longest axis; to ≈ 0.006 km/s at poles
Synodic rotation period	synchronous
Axial tilt	zero
Albedo	1.34±0.10 (geometric)

Calypso is a moon of Saturn. It was discovered in 1980, from ground-based observations, by Dan Pascu, P. Kenneth Seidelmann, William A. Baum, and Douglas G. Currie, and was provisionally designated S/1980 S 25 (the 25th satellite of Saturn discovered in 1980).^[7] Several other apparitions of it were recorded in the following months: S/1980 S 29, S/1980 S 30,^[8] S/1980 S 32,^[9] and S/1981 S 2.^[10] In 1983 it was officially named after Calypso of Greek mythology.^[c] It is also designated Saturn XIV or Tethys C.

Calypso is co-orbital with the moon Tethys, and resides in Tethys' trailing Lagrangian point (L₅), 60 degrees behind Tethys. This relationship was first identified by Seidelmann et al. in 1981.^[11] The moon Telesto resides in the other (leading) Lagrangian point of Tethys, 60 degrees in the other direction from Tethys. Calypso and Telesto have been termed "Tethys trojans", by analogy to the trojan asteroids, and are half of the four presently known trojan moons.

Like many other small Saturnian moons and small asteroids, Calypso is irregularly shaped, has overlapping large craters, and appears to also have loose surface material capable of smoothing the craters' appearance. Its surface is one of the most reflective (at visual wavelengths) in the Solar System, with a visual geometric albedo of 1.34.^[6] This very high albedo is the result of the sandblasting of particles from Saturn's E-ring, a faint ring composed of small, water-ice particles generated by Enceladus' south polar geysers.^[12]

Gallery

Another February 13, 2010 image showing flow-like albedo features
Cassini image from September 23, 2005
Calypso as seen by Voyager 2 (August 1981)

Notes

^ Calculated from Calypso's volume-equivalent sphere radius of 9.5±0.4 km given by Thomas et al. (2020)^[5]^: 2
^ Calculated by multiplying Calypso's volume with its assumed density of 500 kg/m³.
^ Transactions of the International Astronomical Union, Vol. XVIIIA, 1982 (confirms Janus, names Epimetheus, Telesto, Calypso) (mentioned in IAUC 3872: Satellites of Jupiter and Saturn, September 30, 1983)

References

Citations

^ "Calypso". Lexico UK English Dictionary. Oxford University Press. Archived from the original on March 22, 2020.
^ The Emerson Society Quarterly, vol. 50, p. 56, 1968
^ "Calypsonian". Lexico UK English Dictionary UK English Dictionary. Oxford University Press. Archived from the original on March 22, 2020.
^ ^a ^b ^c "Planetary Satellite Mean Orbital Parameters". Jet Propulsion Laboratory. Retrieved 5 June 2023.
^ ^a ^b ^c ^d ^e Thomas & Helfenstein 2020.
^ ^a ^b Verbiscer French et al. 2007.
^ IAUC 3496.
^ IAUC 3549.
^ IAUC 3605.
^ IAUC 3593.
^ Seidelmann Harrington et al. 1981.
^ Mason 2010.

Sources

Marsden, Brian G. (July 31, 1980). "Satellites of Saturn" (discovery). IAU Circular. 3496. Retrieved 2011-12-23.
Marsden, Brian G. (December 11, 1980). "Satellites of Saturn". IAU Circular. 3549. Retrieved 2011-12-23.
Marsden, Brian G. (April 16, 1981). "Satellites of Saturn". IAU Circular. 3593. Retrieved 2011-12-23.
Marsden, Brian G. (May 18, 1981). "Satellites of Saturn". IAU Circular. 3605. Retrieved 2011-12-23.
Marsden, Brian G. (September 30, 1983). "Satellites of Jupiter and Saturn". IAU Circular. 3872. Archived from the original on 2011-07-25. Retrieved 2011-12-23.
Mason, Betsy (February 15, 2010). "New Close-Ups of Saturn's Moons Mimas and Calypso". wired.com. Condé Nast Digital. Retrieved 2011-12-23.
Seidelmann, P. K.; Harrington, R. S.; Pascu, D.; Baum, W. A.; Currie, D. G.; Westphal, J. A.; Danielson, G. E. (1981). "Saturn satellite observations and orbits from the 1980 ring plane crossing". Icarus. 47 (2): 282. Bibcode:1981Icar...47..282S. doi:10.1016/0019-1035(81)90172-X.
Thomas, P. C. (July 2010). "Sizes, shapes, and derived properties of the saturnian satellites after the Cassini nominal mission" (PDF). Icarus. 208 (1): 395–401. Bibcode:2010Icar..208..395T. doi:10.1016/j.icarus.2010.01.025. Archived from the original (PDF) on 2018-12-23. Retrieved 2015-09-04.
Verbiscer, A.; French, R.; Showalter, M.; Helfenstein, P. (9 February 2007). "Enceladus: Cosmic Graffiti Artist Caught in the Act". Science. 315 (5813): 815. Bibcode:2007Sci...315..815V. doi:10.1126/science.1134681. PMID 17289992. S2CID 21932253. Retrieved 20 December 2011. (supporting online material, table S1)
Thomas, P. C.; Helfenstein, P. (July 2020). "The small inner satellites of Saturn: Shapes, structures and some implications". Icarus. 344: 20. Bibcode:2020Icar..34413355T. doi:10.1016/j.icarus.2019.06.016. S2CID 197474587. 113355.

External links

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[6] Calculated from Calypso's volume-equivalent sphere radius of 9.5±0.4 km given by Thomas et al. (2020)^[5]^: 2

[7] Calculated by multiplying Calypso's volume with its assumed density of 500 kg/m³.

[mythology-13] Transactions of the International Astronomical Union, Vol. XVIIIA, 1982 (confirms Janus, names Epimetheus, Telesto, Calypso) (mentioned in IAUC 3872: Satellites of Jupiter and Saturn, September 30, 1983)

[1] "Calypso". Lexico UK English Dictionary. Oxford University Press. Archived from the original on March 22, 2020.

[2] The Emerson Society Quarterly, vol. 50, p. 56, 1968

[3] "Calypsonian". Lexico UK English Dictionary UK English Dictionary. Oxford University Press. Archived from the original on March 22, 2020.

[jpl-satelem-4] "Planetary Satellite Mean Orbital Parameters". Jet Propulsion Laboratory. Retrieved 5 June 2023.

[FOOTNOTEThomas_&_Helfenstein2020-5] Thomas & Helfenstein 2020.

[FOOTNOTEVerbiscer_French_et_al.2007-8] Verbiscer French et al. 2007.

[FOOTNOTEIAUC_3496-9] IAUC 3496.

[FOOTNOTEIAUC_3549-10] IAUC 3549.

[FOOTNOTEIAUC_3605-11] IAUC 3605.

[FOOTNOTEIAUC_3593-12] IAUC 3593.

[FOOTNOTESeidelmann_Harrington_et_al._1981-14] Seidelmann Harrington et al. 1981.

[FOOTNOTEMason2010-15] Mason 2010.

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v t e Saturn
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Geography	Dragon Storm Great White Spot Hexagon Magnetosphere Rings
Moons	S/2009 S 1 Ring moonlets Pan Daphnis Atlas Prometheus Pandora Epimetheus Janus Aegaeon Mimas Methone Anthe Pallene Enceladus Tethys Telesto Calypso Dione Helene Polydeuces Rhea Titan Hyperion Iapetus Inuit group Kiviuq Paaliaq Siarnaq Gallic group Albiorix Norse group Phoebe
Astronomy	Delta Octantis Saturn-crossing minor planets
Exploration	Cassini–Huygens (Huygens) timeline retirement Pioneer 11 Voyager program Voyager 1 Voyager 2
Related	Fiction The Day the Earth Smiled In Saturn's Rings (2018 documentary)
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