Auroral processes in the solar system

Abstract

Studies of the aurora constitute a fundamental component of geophysical research. The observational, theoretical, and modeling advances achieved in understanding terrestrial auroral activity mark a high point in space science and, in particular, in defining linkages between energetics, dynamics, and coupling within the solar wind-magnetospheric-atmospheric system. One of the major achievements of space age technology has been the detection of auroral emissions on other solar system bodies. While the mechanisms responsible for auroral structure on other worlds involve the same basic physics operating on Earth, the settings are of vastly different scale and with sources often unique to each site. Defining an aurora as any optical manifestation of the interaction of extra-atmospheric energetic electrons, ions, and neutrals with an atmosphere, we review the observational inventory of aurora in the solar system and discuss the different steps used for modeling auroral processes. Aurora offers us a unique and extremely valuable remote sensing of magnetic field configuration and is a tracer of plasma interactions. It is an indicator of the atmospheric composition and energy source and can be used for remote sensing of the characteristics of the incident energetic particles. The diversity of magnetic field geometries, plasma interactions, energy sources, and atmospheric constituents, all make comparative auroral studies a rich field, which should lead us to further understanding of interactions taking place at different solar system bodies.