Auroral Radio Emission from the Solar System Planets

Five planets of our solar system with well-developed and extended magnetospheres (Earth, Jupiter, Saturn, Uranus, and Neptune) emit intense coherent non-thermal radio emission which appears as one of the most attractive and spectacular phenomena of the interaction between the solar wind and planetary magnetospheres. The strongest component of the planetary radio emission is auroral radiation usually originated in the auroral acceleration regions of the magnetospheres. This emission is observed at frequencies close to the local cyclotron frequency of the electrons. The most widely accepted generation mechanism is the electron cyclotron maser driven by charged particles accelerated in strong field-aligned electric fields. In generally, the characteristics of the auroral radio emission are merely depending on the dynamics and topology of the magnetosphere as well as the solar wind environment. This makes this radiation to be an important remote diagnostic tool of planetary auroral processes. This paper is a short review of the new theoretical and observational aspects of auroral radio emission study with main focus on the radiations from the Earth (terrestrial auroral kilometric radiation), Jupiter (Jovian hectometer and decametric radiations) and Saturn (Saturnian kilometric radiation).