

Ganymede is a natural satellite of Jupiter and the largest natural satellite in the Solar System. Completing an orbit in a little more than seven days, it is the seventh satellite and third Galilean satellite from Jupiter.
| Links | Ganymede_files\Links.htm |
| Info | Ganymede_files\Info.htm |

Ganymede is Jupiter's largest moon.
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Discovery
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| Discovered by |
G. Galilei S. Marius |
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| Discovery date | January 11, 1610 | ||||||
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Designations
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| Alternate name | Jupiter III | ||||||
| Adjective | Ganymedian, Ganymedean | ||||||
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Orbital
characteristics
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| Periapsis | 1 069 200 km | ||||||
| Apoapsis | 1 071 600 km | ||||||
| Mean orbit radius | 1 070 400 km | ||||||
| Eccentricity | 0.001 3 | ||||||
| Orbital period | 7.154 552 96 | ||||||
| Average orbital speed | 10.880 km/s | ||||||
| Inclination | 0.20° (to Jupiter's equator) | ||||||
| Satellite of | Jupiter | ||||||
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Physical characteristics
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| Mean radius | 2634.1 ± 0.3 km (0.413 Earths) | ||||||
| Surface area | 87.0 million km2 (0.171 Earths) | ||||||
| Volume | 7.6 × 1010 km3 (0.0704 Earths) | ||||||
| Mass | 1.4819 × 1023 kg (0.025 Earths) | ||||||
| Mean density | 1.936 g/cm3[2] | ||||||
| Equatorial surface gravity | 1.428 m/s2 (0.146 g)[e] | ||||||
| Escape velocity | 2.741 km/s | ||||||
| Rotation period | synchronous | ||||||
| Axial tilt | 0–0.33° | ||||||
| Albedo | 0.43 ± 0.02 | ||||||
| Surface temp. K |
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| Apparent magnitude | 4.61 (opposition) | ||||||
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Atmosphere
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| Surface pressure | trace | ||||||
| Composition | oxygen | ||||||

Ganymede participates in orbital resonances with Europa and Io: for every orbit of Ganymede, Europa orbits twice and Io orbits four times.
Jupiter's big moon Ganymede is not only the size of a planet -- it sounds like one too, as heard in audio recordings made from data returned by NASA's Galileo spacecraft released today.
Characterized by a soaring whistle and hissing static, Ganymede's song reveals that the Solar System's largest moon is also the only one known to possess a planet-like, self- generated magnetic cocoon called a magnetosphere, which shields the moon from the magnetic influence of its giant parent body, Jupiter

The average
density of Ganymede, 1.936 g/cm, suggests a composition of approximately equal
parts rocky material and water, which is mainly in the form of ice.
Ganymedian surface is a mix of two types
of terrain: very old, highly
cratered,
dark regions and somewhat younger (but still ancient), lighter regions marked
with an extensive array of grooves and ridges.
Map of Ganymede

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Ganymede orbits Jupiter at a distance of 1, 070, 400 km, third among the Galilean satellites, and completes a revolution every seven days and three hours.
Galileo's C9 orbit around Jupiter
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| Approaching Callisto with Jupiter visible in the distance. | Getting really close to Callisto. |
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| Having flown by Callisto's darkside we see a "sunrise". | Goodbye to Callisto. |
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| Approaching the next satellite - Ganymede. | Closest to Ganymede, about 80000 km. |
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| A nice view - Callisto's tiny crescent above Ganymede. | Zooming in on Io transiting the face of Jupiter. |
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| Nearing the end of the Io transit. | Towards the end of the orbit. |
Pictures of Ganymede taken by Voyager Basemap Mosaics
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