In this book, Syun-Ichi Akasofu attempts to explain auroral phenomena, particularly their explosive activity, known as auroral substorms, as a significant electrical discharge within a comet-shaped space surrounding the Earth, called the magnetosphere. For the discharge process, its power supply (auroral dynamo), transmission (circuit), and finally dissipation (observed auroral phenomena) are described by following the power flow in terms of electric current.
The power is accumulated in an early stage, but the magnetosphere becomes unstable and releases the accumulated energy explosively. It has taken the author 60 years to reach this tentative hypothesis. A similar approach is also attempted to explain solar flares (also explosive), although the difference in the energy involved is very large.
The author participated in space physics from the early days of the discipline, affording him fortunate opportunities to work with pioneering researchers in the field. Since then, he has worked with many colleagues along the way. He describes many stories and episodes, including several observational events. Like any other field, auroral physics and solar physics have well-established or widely accepted theories. Syun-Ichi Akasofu encountered them in most subjects, but he believes he could advance one step beyond them by taking the electric current approach.