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Ganymede

Ganymede Moon Gemini Visible Level 3 Medium telescope (6-8") - Timing dependent
Credit: Kevin M. Gill. License: CC BY 2.0. (Wikimedia Commons)
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Properties

Magnitude 4.6
Angular Size 1.7 arcmin
Type: Moon
Distance: 0.007 AU
Orbital Period: 7.2 days
Diameter: 2,631 km
Atmosphere: Thin oxygen
Features: Craters, grooves
Largest moon in solar system.

Position & Identifiers

RA 07h 05m 44.7s
Dec +22° 56' 28.0"
Constellation Gemini
Catalog Ganymede
Ganymede — NASA/JPL
Image: NASA/JPL · PIA25721

Physical Properties

Diameter 2,631 km (0.21× Earth)
Mass 1.48e23 kg
Albedo 0.44 (44% reflected)
Temperature -193°C to -113°C
Rotation 7.2 days
Atmosphere Thin oxygen
Surface Craters, grooves
Angular Size 0.7″ (current)

Orbital Properties

Semi-major Axis 0.0072 AU (1,070,373 km)
Eccentricity 0.0010
Inclination 0.20°
Orbital Period 7.2 days
Distance 4.989 AU (41.5 light-min)
Elongation 99.1° Good

Observing Tips

Best Months May , June , July
Visibility Binoculars
Where to Look Near Jupiter
Notes Largest moon in solar system.

Parent Body

Orbits Jupiter
Orbital Period 7.16 days
Distance 1,070,373 km

Discovery

Discovered by Galileo Galilei
Date 1610

Current Ephemeris

4.989
AU from Earth
746.3M
km
0.7″
Angular Size
99°
Elongation

Visibility

Set a location in User Settings to see visibility data.

Community Photos (1)

Credit: Kevin M. Gill. License: CC BY 2.0. (Wikimedia Commons)

Credit: Kevin M. Gill. License: CC BY 2.0. (Wikimedia Commons)

Skybred Feb 28, 2026