A magnetosphere is the region around a body in which the body's magnetic interaction controls charged-particle motion and its response to the surrounding plasma. A planet with an intrinsic magnetic field can support a compressed dayside and an extended magnetotail in the solar wind. Magnetospheric currents must be distinguished from the internal field when inferring a planetary dynamo.
An induced magnetosphere is maintained by the interaction of an external magnetized plasma flow with a conducting ionosphere or atmosphere. Its currents and draped magnetic field do not establish an internal planetary dynamo. Venus is a central example; Mars combines this interaction with localized crustal fields.
