Dione (moon)

Dione
	Dione photographed in natural light by the; Cassini spacecraft in 2008
Discovery
Discovered by	Giovanni Cassini
Discovery date	30 March 1684
Designations
Designation	Saturn IV
Pronunciation	/daɪˈoʊniː/
Named after	Διώνη Diōnē
Adjectives	Dionean /daɪəˈniːən/
Orbital characteristics
Semi-major axis	377396 km
Eccentricity	0.0022
Orbital period (sidereal)	2.736915 d
Inclination	0.019° (to Saturn's equator)
Satellite of	Saturn
Physical characteristics
Dimensions	1128.8 × 1122.6 × 1119.2 km
Mean radius	561.4±0.4 km
Surface area	3964776.51 km2
Mass	(1.0954868±0.0000246)×1021 kg (1.834×10−4 Earths)
Mean density	1.4781±0.0032 g/cm3
Surface gravity	0.232 m/s2
Escape velocity	0.51 km/s
Synodic rotation period	2.736915 d ; (synchronous)
Axial tilt	zero
Albedo	0.998±0.004 (geometric)
Temperature	87 K (−186°C)
Apparent magnitude	10.4

Dione (/daɪˈoʊni/), also designated Saturn IV, is the fourth-largest moon of Saturn. With a mean diameter of 1,123 km and a density of about 1.48 g/cm³, Dione is composed of an icy mantle and crust overlying a silicate rocky core, with rock and water ice roughly equal in mass. Its trailing hemisphere is marked by large cliffs and scarps called chasmata; the trailing hemisphere is also significantly darker compared to the leading hemisphere.

The moon was discovered by Italian astronomer Giovanni Domenico Cassini in 1684 and is named after the Titaness Dione in Greek mythology. Dione was first imaged up-close by the Voyager 1 space probe in 1980. Later, the Cassini spacecraft made multiple flybys of Dione throughout the 2000s and 2010s as part of its campaign to explore the Saturn system.

^ "Dione". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 22 March 2020.
"Dione". Merriam-Webster.com Dictionary.
^ JPL (March 13, 2007) Cassini: Dionean Linea Archived 2021-10-26 at the Wayback Machine
^ Len Krisak (2011) Virgil's Eclogues, p. 71
^ ^a ^b "Data for our solar system". Exp.arc.nasa.gov. 20 April 2003. Archived from the original on 9 March 2005. Retrieved 21 May 2007.
^ ^a ^b Cite error: The named reference Roatsch2009 was invoked but never defined (see the help page).
^ ^a ^b ^c Jacobson, Robert. A. (1 November 2022). "The Orbits of the Main Saturnian Satellites, the Saturnian System Gravity Field, and the Orientation of Saturn's Pole*". The Astronomical Journal. 164 (5): 199. Bibcode:2022AJ....164..199J. doi:10.3847/1538-3881/ac90c9. S2CID 252992162.
^ Cite error: The named reference Solar System Exploration was invoked but never defined (see the help page).
^ Cite error: The named reference Verbiscer et al. 2007 was invoked but never defined (see the help page).
^ Cite error: The named reference Observatorio ARVAL was invoked but never defined (see the help page).

[1] "Dione". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 22 March 2020.
"Dione". Merriam-Webster.com Dictionary.

[2] JPL (March 13, 2007) Cassini: Dionean Linea Archived 2021-10-26 at the Wayback Machine

[3] Len Krisak (2011) Virgil's Eclogues, p. 71

[exp.arc.nasa.gov-4] "Data for our solar system". Exp.arc.nasa.gov. 20 April 2003. Archived from the original on 9 March 2005. Retrieved 21 May 2007.

[Roatsch2009-5] Cite error: The named reference Roatsch2009 was invoked but never defined (see the help page).

[Jacobson2022-6] Jacobson, Robert. A. (1 November 2022). "The Orbits of the Main Saturnian Satellites, the Saturnian System Gravity Field, and the Orientation of Saturn's Pole*". The Astronomical Journal. 164 (5): 199. Bibcode:2022AJ....164..199J. doi:10.3847/1538-3881/ac90c9. S2CID 252992162.

[Solar_System_Exploration-7] Cite error: The named reference Solar System Exploration was invoked but never defined (see the help page).

[Verbiscer_et_al._2007-8] Cite error: The named reference Verbiscer et al. 2007 was invoked but never defined (see the help page).

[Observatorio_ARVAL-9] Cite error: The named reference Observatorio ARVAL was invoked but never defined (see the help page).

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