A magnetosphere is formed when a stream of charged particles, such as the solar wind interact with and are deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter, Saturn, Uranus, and Neptune. Jupiter's moon Ganymede has a small magnetosphere - but it resides entirely within the magnetosphere of Jupiter, giving rise to complex interactions. The ionospheres of weakly ma… (More on Magnetosphere)