This book explores the opportunities, the potential and the hazards of Earth's immediate space environment. It covers the physical characteristics of this portion of space, the influence of deeper space, observing and forcasting tools, the problem of space debris, the evolution of satellites, the different orbits and their uses, Earth's place in the solar system and its influence on climate and weather, the sun and its action on our planet, asteroid and comets and the means to detect them, laws and regulations, the political actors and role of nations.