Sun Not Quiet

Press, Volume CV, Issue 31003, 8 March 1966, Page 11

Sun Not Quiet

The International Year of the Quiet Sun is over and the sun has obediently stopped being quiet. The 11-year cycle of solar activity began climbing towards its 1971 maximum during January when a series of solar storms shattered the calm.

Throughout the inner solar system the wind of atomic particles blowing outwards from the sun blew harder and faster, reaching nearly one-and-a-half million miles an hour—twice the normal velocity. When a gust of the solar wind comes near the earth it raises a magnetic storm and may cause radio black-outs and colourful auroral displays. For many years these effects have been studied but their cause, the solar wind, was unknown. Discovered by early space probes such as Pioneer V and the Luniks, the solar wind has its origin low in the solar corona and is enhanced whenever a flare occurs on the surface of thp sun. The first regular measurements of the solar wind were radioed to earth by Mariner II on its historic journey to Venus. Pioneer Chart At the moment the interplanetary probe Pioneer VI is on duty about six million miles out in space. Launched last December it is the first of seven new Pioneer vehicles whose goal is to chart the changes in space phenomena

throughout an entire solar cycle. They carry instruments for detecting the particles of the solar wind and finding their composition and velocity, as well as apparatus for measuring cosmic rays and the strength of the solar magnetic field. These phenomena are inter-related in a complex fashion and little is known of the way they vary when storms rage on the sun. Results from the new Pioneers will lead to a better understanding of the weather conditions in the far-from-empty space around us.