Polydeuces (moon)

Polydeuces
	Saturn's moon Polydeuces, as imaged by the Cassini spacecraft
Discovery
Discovered by	Cassini Imaging Science Team
Discovery date	October 24, 2004
Designations
Designation	Saturn XXXIV
Pronunciation	/ˌpɒlɪˈdjuːsiːz/
Named after	Πολυδεύκης Polydeykēs
Alternative names	Dione C; S/2004 S 5
Adjectives	Polydeucean /ˌpɒlɪdjuːˈsiːən/ Polydeucian /ˌpɒlɪˈdjuːsiən/
Orbital characteristics
Semi-major axis	377,396 km
Eccentricity	0.0192
Orbital period	2.736915 d
Inclination	0.1774 ± 0.0015°
Satellite of	Saturn
Group	L5 Dione trojan
Physical characteristics
Dimensions	3 × 2.5 × 2 km
Mean radius	1.3 ± 0.4 km
Mass	1–5 ×1013 kg
Rotation period	assumed synchronous

Polydeuces /ˌpɒlɪˈdjuːsiːz/, or Saturn XXXIV, is a small natural satellite of Saturn that is co-orbital with the moon Dione and librates around its trailing Lagrangian point (L₅). Its diameter is estimated to be 2–3 km.^[5] Dione's other co-orbital moon is Helene, which is bigger and located at the leading L4 point.^[6]

Polydeuces was discovered by the Cassini Imaging Team on October 24, 2004,^[7] in images taken on October 21, 2004,^[8]^[9] 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.^[7]

Of the four known Lagrangian co-orbitals in the Saturn system ('trojan moon'), Polydeuces wanders the farthest from its Lagrangian point: its distance behind Dione varies from 33.9° to 91.4° with a period of 790.931 days (for comparison, L₅ trails Dione by 60°).^[4] Polydeuces's 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's orbital radius also varies by about ± 7660 km with respect to Dione's.^[7]

The name Polydeuces was approved by the IAU Working Group on Planetary System Nomenclature on January 21, 2005.^[10] In Greek mythology, Polydeuces is another name for Pollux, twin brother of Castor, son of Zeus and Leda.

Due to gravitational interactions with Dione, its surface may be in hydrostatic equilibrium but not its interior, similar to Methone being in hydrostatic equilibrium due to interactions with Mimas.

Animation of Polydeuces's orbit relative to Saturn and Dione
Polydeuces · Helene · Dione · Saturn

Notes[]

^ Jump up to: ^a ^b The mean semi-major axis and period must be identical to Dione's.
^ based on density 0.5–2 g/cm³

References[]

^ "Polydeuces". Lexico UK Dictionary. Oxford University Press.
^ Lundström (1997) Eranos, v. 95
^ Levin (1971) Apollonius' Argonautica, v. 1, p. 139
^ Jump up to: ^a ^b ^c ^d Spitale Jacobson et al. 2006.
^ Jump up to: ^a ^b ^c 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.
^ Patrick Moore; Robin Rees (2014). Patrick Moore's Data Book of Astronomy. Cambridge University Press. p. 214. ISBN 978-1-139-49522-6.
^ Jump up to: ^a ^b ^c Murray Cooper et al. 2005.
^ Porco Baker et al. 2005.
^ IAUC 8432.
^ IAUC 8471.

External links[]

Listen to this article (2 minutes)

Menu

0:00

This audio file was created from a revision of this article dated 6 February 2010, and does not reflect subsequent edits.

[Dione-4] Jump up to: ^a ^b The mean semi-major axis and period must be identical to Dione's.

[density-7] sed on density 0.5–2 g/cm³

[1] "Polydeuces". Lexico UK Dictionary. Oxford University Press.

[2] Lundström (1997) Eranos, v. 95

[3] Levin (1971) Apollonius' Argonautica, v. 1, p. 139

[FOOTNOTESpitale_Jacobson_et_al.2006-5] Jump up to: ^a ^b ^c ^d Spitale Jacobson et al. 2006.

[Thomas2010-6] Jump up to: ^a ^b ^c 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.

[8] Patrick Moore; Robin Rees (2014). Patrick Moore's Data Book of Astronomy. Cambridge University Press. p. 214. ISBN 978-1-139-49522-6.

[FOOTNOTEMurray_Cooper_et_al._2005-9] Jump up to: ^a ^b ^c Murray Cooper et al. 2005.

[FOOTNOTEPorco_Baker_et_al._2005-10] Porco Baker et al. 2005.

[FOOTNOTEIAUC_8432-11] IAUC 8432.

[FOOTNOTEIAUC_8471-12] IAUC 8471.

[1]

[2]

[3]

[4]

[a]

[5]

[b]

[6]

[7]

[8]

[9]

[10]

hide v t Moons of Saturn
Listed in approximately increasing distance from Saturn as of epoch JD 2459200.5.
Ring shepherds	S/2009 S 1 Ring moonlets Pan Daphnis Atlas Prometheus Pandora
Co-orbitals	Epimetheus Janus
G Ring	Aegaeon
Alkyonides	Methone Anthe Pallene
Inner large (with trojans)	Mimas Enceladus Tethys Telesto Calypso Dione Helene Polydeuces
Outer large	Rhea Titan Hyperion Iapetus
Inuit group (7)	Kiviuq Ijiraq Paaliaq Saturn LX S/2004 S 31 Tarqeq Siarnaq
Norse group (46)	Phoebe Skathi S/2004 S 37 S/2007 S 2 Skoll Hyrrokkin Greip Mundilfari S/2004 S 13 (?) S/2006 S 1 S/2007 S 3 (?) Suttungr Saturn LIV Jarnsaxa Narvi Bergelmir Hati S/2004 S 17 (?) S/2004 S 12 (?) Saturn LIX Farbauti Thrymr Bestla S/2004 S 7 (?) Aegir Saturn LXI Saturn LV Saturn LVII Saturn LXII Saturn LVI S/2006 S 3 Saturn LXV Kari S/2004 S 28 Loge Saturn LXVI Fenrir Ymir Surtur Saturn LXIII S/2004 S 21 S/2004 S 39 S/2004 S 36 Fornjot Saturn LXIV Saturn LVIII
Gallic group (4)	Albiorix Bebhionn Erriapus Tarvos
Prograde outer satellites	S/2004 S 24
Rings of Saturn Cassini–Huygens Themis Chiron S/2004 S 6 S/2004 S 4 S/2004 S 3 In fiction

show v t Saturn
Outline of Saturn
Geography	Dragon Storm Great White Spot Hexagon Magnetosphere Rings
Moons	S/2009 S 1 Ring moonlets Pan Daphnis Atlas Prometheus S/2004 S 6 S/2004 S 4 S/2004 S 3 Pandora Epimetheus Janus Aegaeon Mimas Methone Anthe Pallene Enceladus Tethys Telesto Calypso Dione Helene Polydeuces Rhea Titan Hyperion Iapetus Kiviuq Ijiraq Phoebe Paaliaq Skathi S/2004 S 37 Albiorix S/2007 S 2 Saturn LX Bebhionn Erriapus Skoll S/2004 S 31 Siarnaq Tarqeq S/2004 S 13 Greip Hyrrokkin Jarnsaxa Tarvos Mundilfari S/2006 S 1 S/2004 S 17 Bergelmir Narvi Saturn LIV Suttungr Hati S/2004 S 12 Saturn LIX Farbauti Thrymr Saturn LXI Aegir S/2007 S 3 Bestla S/2004 S 7 Saturn LV Saturn LVI Saturn LVII Saturn LXII S/2006 S 3 Saturn LXVI Fenrir S/2004 S 28 Surtur Kari Saturn LXV Ymir S/2004 S 21 S/2004 S 24 Loge S/2004 S 36 S/2004 S 39 Saturn LXIII Saturn LXIV Fornjot Saturn LVIII
Astronomy	Delta Octantis Saturn-crossing minor planets
Exploration	Cassini–Huygens (Huygens) timeline retirement Pioneer 11 Voyager program Voyager 1 Voyager 2
Related	Fiction Moons The Day the Earth Smiled In Saturn's Rings (2018 documentary)

Polydeuces (moon)

Contents

See also[]

Notes[]

References[]

Further reading[]

External links[]