The Sun and its Role in the Heliosphere (Advances in Space Research)

The Heliosphere is a large volume of space dominated by the expanding solar atmosphere. Spacecraft at 60 Astronomical Units from the Sun (1 Astronomical Unit = 150 Million Kilometers) have not yet encountered the boundary where the Heliosphere ends and interstellar space begins. This publication contains 22 papers, most observational, some theoretical, on heliospheric topics. Most of the observations reported are either from the recently commissioned SOHO (Solar and Heliospheric Observatory) spacecraft or from the Ulysses spacecraft which had completed the first ever polar obit of the Sun. The SOHO based papers include the first observations of the extended solar corona in the ultraviolet domain, which allow a description of the plasma velocities distribution in the region where solar wind is accelerated, and "in situ" energetic particles result. The Ulysses based papers include descriptions of how the solar wind parameters (velocity, momentum flux, composition etc.) vary from the disturbed low velocity regime close to the solar equator, to the region of fast steady flow in solar polar latitudes.