![]() Saturn's moon Polydeuces. |
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Discovery | |||||||
Discovered by | Cassini Imaging Science Team | ||||||
Discovered on | 24 October, 2004 | ||||||
Orbital characteristics | |||||||
mean Semimajor axis | 377,396 km[1] | ||||||
Eccentricity | 0.0192[2] | ||||||
Orbital period | 2.736915 d[1] | ||||||
Inclination | 0.1774 ± 0.0015°[2] | ||||||
Is a satellite of | Saturn | ||||||
Physical characteristics | |||||||
Mean diameter | 3.5 km[3] | ||||||
Mass | 1 − 5 ×1013 kg [4] | ||||||
Mean density | unknown | ||||||
Surface gravity | unknown | ||||||
Rotation period | assumed synchronous | ||||||
Axial tilt | unknown | ||||||
Albedo | unknown | ||||||
Surface temperature |
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Atmosphere | none |
Polydeuces (Template:PronEng POL-i-DEW-seez, or as Greek Πολυδεύκης) is a very small natural satellite of Saturn that is co-orbital with Dione and librates around the trailing Lagrangian point (L5). Its diameter is estimated to be about 3.5 km.[3]
Polydeuces was discovered by the Cassini Imaging Team on October 24, 2004[5] in images taken on October 21, 2004,[6],[3] and given the temporary designation S/2004 S 5. Subsequent searches of earlier Cassini imaging showed it in images as far back as April 9, 2004[5]. Polydeuces is also designated as Saturn XXXIV.
Of the known Lagrangian co-orbitals in the Saturn system, Polydeuces wanders the farthest from its Lagrangian point. The libration takes it away from the L5 by up to 31.4° in the direction away from Dione, and 26.1° towards it with a period of 790.931 days (for comparison L5 trails Dione by 60°).[2] Polydeuces' libration is large enough that it takes on some qualities of a tadpole orbit, as evidenced by the clear asymmetry between excursions towards and away from Dione. In the course of one such cycle, Polydeuces' orbital radius also varies by about ± 7660 km with respect to Dione's.[5]
The name Polydeuces was approved by the IAU Working Group on Planetary System Nomenclature on January 21, 2005.[7] In Greek mythology, Polydeuces is another name for Pollux, twin brother of Castor, son of Zeus and Leda.
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