The Sun and the Earth

Abstract

The Sun's action on the Earth is fundamentally responsible for maintaining the physical conditions that support life on the land, in the oceans, and in the atmosphere, and a comprehensive understanding of this action should be a central concern of scientific endeavor. The Sun's influence goes beyond providing energy to the biosphere and maintaining the Earth's climate and weather; it strongly affects the Earth's upper atmosphere and ionosphere as well as the magnetosphere, the region of space permeated by the terrestrial magnetic field and occupied by ionized gases. Flares and other solar disturbances can produce strong reactions in the Earth's ionosphere, magnetic field, and space plasma environment, often within 20 minutes of onset. As human activity extends into space, and to the Moon and planets, scientific understanding of solar‐terrestrial interactions and, more generally, of the space environment's physics will assume increasing importance.