Dione (moon)
Moon of Saturn / From Wikipedia, the free encyclopedia
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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.
Discovery | |
---|---|
Discovered by | Giovanni Cassini |
Discovery date | 30 March 1684 |
Designations | |
Designation | Saturn IV |
Pronunciation | /daɪˈoʊniː/[1] |
Named after | Διώνη Diōnē |
Adjectives | Dionean[2] /daɪəˈniːən/[3] |
Orbital characteristics | |
377396 km | |
Eccentricity | 0.0022[4] |
2.736915 d[4] | |
Inclination | 0.019° (to Saturn's equator) |
Satellite of | Saturn |
Physical characteristics | |
Dimensions | 1128.8 × 1122.6 × 1119.2 km[5] |
Mean radius | 561.4±0.4 km[5][6] |
3964776.51 km2[7] | |
Mass | (1.0954868±0.0000246)×1021 kg[6] (1.834×10−4 Earths) |
Mean density | 1.4781±0.0032 g/cm3[6] |
0.232 m/s2 | |
0.51 km/s | |
2.736915 d (synchronous) | |
zero | |
Albedo | 0.998±0.004 (geometric)[8] |
Temperature | 87 K (−186°C) |
10.4 [9] | |
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.