The spacecraft NASA’s “Juno” (“Juno”) for four years revolves around Jupiter, along the way, watching his companions. But now he first photographed from a distance of 100 000 km of the North pole of one of them – Ganymede, where there are constant plasma “rains”.
Ganymede is extremely interesting. It is the largest moon in the Solar system – its diameter is 5267 miles (that is 8% larger than the diameter of mercury). It is composed of water ice and frozen silicate rocks. Some scientists believe that beneath the surface of Ganymede can be made from the water of the ocean.
Among his many brothers in the Solar system, it stands out the presence of its own magnetosphere, which, presumably, was due to convection (a type of heat transfer when energy is transferred by the flow of gas or liquid) in its saturated liquid iron core.
A little bit about plasma “rains”. On Earth, where there is atmosphere, solar radiation is ionized, creating a distinctive glow at the poles. Pictures “Juno” showed that deprived of the atmosphere of Ganymede streams of charged particles – in essence, this plasma “rains” under the influence of a magnetic field to freely rush to the poles, turning the ice into a friable mass, while at the equator it has a regular crystalline structure.
In NASA hopes that the results obtained with the “Juno” information will expand the understanding of the evolution of all 79 of the moons of Jupiter since their inception and will help in the preparation of future missions, in particular, European American JUICE and Europa Clipper, to be held respectively in 2022 and the years 2023-25.
Source — NASA