This book is an insight in to the thermodynamics and electromagnetic forces of the sun-earth interactions. The E (dynamo) region of the equatorial ionosphere consists of 2 layers of currents responsible for the quiet solar daily variations in the Earth's magnetic field. One is the Worldwide solar quiet daily variation, WSq (altitude 118 7 km), responsible for the global quiet daily variation observed in the earth's magnetic field and the other is the Equatorial Electrojet; an intense current flowing eastward in the low latitude ionosphere within the narrow region flanking the dip equator (altitude 106 2 km). The book surveys the characteristics of the Equatorial Electrojet and further highlights the methods of estimation of the strength of the EEJ from a research work."