Solar Wind

Abstract

The circumstances that create the solar wind were established from ground based observations, and the essential physics is illustrated directly by those early observations. For instance, the continual emission of solar corpuscular radiation in all directions from the Sun was indicated by the anti-solar acceleration of the gaseous comet tails. The million degree temperature of the corona of the Sun was recognized, and it was appreciated that the corona is strongly bound by the gravitational field of the Sun. As a consequence of the thermal conductivity and the extended active heating of the corona, themillion degree temperature extends far out into space, to where the gas density is very small, and the gravitational binding energy falls below the enthalpy of the gas. The outer corona expands away to infinity, reaching supersonic speed. This is, of course, the solar wind, or solar corpuscular radiation, responsible for the anti-solar comet tails.