The animations were created using AVS . The Magnetosphere of Neptune Neptune, usually the eighth planet from the sun in distance, is a gas giant and the sixth planet found to have a strong internal magnetic field. Voyager 2 approached Neptune more closely than any planet since it left Earth some 12 years before. Closest approach was only one-fifth of a planetary radius above the visible cloud deck. Like Jupiter and Saturn, but unlike Uranus, Neptune possess an internal source of heavy-ion plasma, its moon Triton, for its magnetosphere.
Triton has both an atmosphere and a surprisingly substantial ionosphere.
Located about 14 RN from Neptune and resembling the planet Pluto in many respects, Triton is a source of plasma which diffuses into the inner magnetosphere of Neptune. Outside several planetary radii, Neptune's magnetic field can be represented by a dipole moment offset by half a planetary radius from the center of Neptune and tilted by 47 degrees with respect to the spin axis of the planet. So Neptune's magnetosphere provides a unique case for studies of magnetospheres with greatly varying intrinsic properties. Plasma parameters for the simulation are taken solar wind measurements by Voyager 2 just prior to its leaving the undisturbed solar wind. An animation of the magnetic field structure derived from this simulation and based upon the geometry at the time of the 1989 Voyager encounter will be available soon.