SOLAR ENERGETIC PARTICLES - A PARADIGM SHIFT

Laboratory for High Energy Astrophysics, NASA Goddard Space Flight Center, Greenbelt, MarylandThe first evidence of high‐energy particles from the Sun was obtained 50 years ago when Forbush [1946] used sea‐level ion chambers to study the large solar events of February and March of 1942. Over the next 20 years, observation of these solar energetic particle (SEP) events using neutron monitors and riometers (that measure radio opacity of the ionosphere) and, later, with detectors on balloons and satellites, led to an extensive body of knowledge on the time profiles, spectra and particle abundance in the large events. Meanwhile, there was already a rich history of the study of solar flares spanning 100 years since the first observations reported by Carrington [1860]. With no knowledge of the existence of coronal mass ejections (CMEs) [Kahler 1992], it was tempting to assume that the particle acceleration somehow occurred in spatial and temporal conjunction with the solar flare itself. Thus the “solar flare myth” [Gosling 1993] of particle acceleration began nearly 30 years ago. Copyright 1995 by the American Geophysical Union.