Size comparison: Earth vs Ganymede

Comparison of the size between Earth and Ganymede, Jupiter's moon, seventh natural satellite of this planet.

Ganymede is the largest natural satellite in Jupiter, but also the largest natural satellite in the solar system. Its composition is half made of silicate rocks and half of water ice. With a diameter similar to Mercury, its mass is equivalent to 45% of that of Mercury which is composed of rocks and metals. Its liquid nucleus is rich in iron. There is an ocean under surface ice. It is believed that this ocean could contain water. We do not know the reasons for his geology with dark surfaces and clear regions covered with wide grooves. This could be the result of a tectonic activity.

Object	Earth	Ganymede
Type	Rocky planet	Rocky satellite
Age	4.54 billion years	4 billion years
Population	7.7 billion	0
Diameter	12,742 km	5,268 km
Mean radius	6,371 km	2,634 km
Mass	5.97 × 1024 kg	1.48 × 1023 kg
Orbital period	365 days	7.1 days
Surface temperature (average)	288 K 14.9 °C 58.7 °F	110 K -163 °C -261.4 °F
Surface gravity	9.8 m/s²	1.42 m/s²
Mean density	5.5 g/cm3	1.93 g/cm3
Orbital distance	150 million km	1,070,400 km
Circumference	40,075 km	16,549 km
Surface area	510 million km²	87 million km²
Volume	1.08 × 1012 km3	0.76 × 1011 km3
Escape velocity	11.1 km/s	2.63 km/s
Average orbital speed	29.78 km/s	2.74 km/s
Semi major axis	149 million km	1.07 million km
Inclination	7.1°	2.21°
Surface pressure	101.3 kPa	1.2 μPa
Atmosphere composition	78% nitrogen (N2), 21% oxygen (O2), ~ 1% water vapor, 0.9% argon, 0.04% carbon dioxide	oxygen
Crust composition	60% silica, 16% alumina, 6% lime, 6% iron oxide, 4% magnesia, 3% sodium oxide, 2% potassium oxide	silicate, ice, liquid water
Distance from the Milky Way center	27,200 light years	27,200 light years

Note: if one of the objects is not visible, it just means that it is too tiny to be displayed compared to the other one.