How exactly is the solar wind propelled?
Non-stop streams of electrons and atomic nuclei pour from the Sun in all directions, in slow and fast electric windstreams travelling at speeds of 300 to 800 kilometres per second. This solar wind and its variations have a profound effect on the Earth’s space environment, as investigated by the Cluster and Double Star projects. The SOHO spacecraft has discovered sources of the solar wind in the Sun’s atmosphere, and has watched its particles being accelerated. Solar Orbiter will detect the solar-wind particles close to where they escape through funnels and holes in the Sun’s magnetic field. Simultaneously it will watch the sources and accelerators of the wind more closely than ever before. How does the Sun rule interplanetary space? The solar wind fills a gigantic bubble all around the Sun, called the heliosphere. It extends far beyond the realm of the planets. ESA’s spacecraft Ulysses, in its unique flights over the poles of the Sun, has given a comprehensive impression of storms and
