Comparative magnetospheres: lessons for Earth Original Research Article

The comparative study of various magnetospheres is not only interesting in itself but also useful for understanding better many aspects of the magnetosphere of Earth. Scaling relations can be tested over a much wider parameter range than that provided by Earth alone. Comparison of Earth with other magnetospheres tells us about the relative importance of the ionosphere, the significance of kinetic effects, the dependence on the geometrical configuration of rotation axis, magnetic dipole, and solar wind flow direction, and the role of the external magnetic field. Processes such as magnetic field line reconnection and auroral particle acceleration are common to many different magneto-spheres and can be better understood when observed in different contexts. Diffusive transport across closed magnetic field lines plays a special role in the magnetospheres both of Jupiter and of Earth. Finally, some properties and limitations of numerical simulation work are illuminated by application under distinct conditions provided by different magnetospheres, in particular Jupiter and Earth.