by Juno’s June 7, 2021 flyby of Ganymede is the closest a spacecraft has come to Jupiter’s largest moon since NASA’s Galileo spacecraft made its close approach back on May 20, 2000.
Ganymede has a diameter of 5,268 km (3,273 miles), around 8% larger than that of the planet Mercury and much larger than Pluto.
Discovered in 1610, it is the only moon in the Solar System to have its own magnetosphere, which causes aurorae in regions circling its north and south poles.
As Ganymede has no atmosphere, the surface at its poles is constantly being bombarded by plasma from the magnetosphere of Jupiter.
This bombardment has a dramatic effect on the moon’s ice.
It has three main layers: a sphere of metallic iron at the center, a spherical shell of rock surrounding the core, and a spherical shell of mostly ice surrounding the rock shell and the core.
The ice shell on the outside is very thick, maybe 800 km (497 miles) thick.
Source
Ganymede has a diameter of 5,268 km (3,273 miles), around 8% larger than that of the planet Mercury and much larger than Pluto.
Discovered in 1610, it is the only moon in the Solar System to have its own magnetosphere, which causes aurorae in regions circling its north and south poles.
As Ganymede has no atmosphere, the surface at its poles is constantly being bombarded by plasma from the magnetosphere of Jupiter.
This bombardment has a dramatic effect on the moon’s ice.
It has three main layers: a sphere of metallic iron at the center, a spherical shell of rock surrounding the core, and a spherical shell of mostly ice surrounding the rock shell and the core.
The ice shell on the outside is very thick, maybe 800 km (497 miles) thick.
Source
