HISTORY OF SOLAR PROTON EVENT OBSERVATIONS

Solar flare effects and related solar particle emissions can adversely affect the near-earth spatial environment. It is desirable to be able to predict when solar proton events will occur, how large they will b e, and how long they will last. We examine the evolution of solar prot on event observations and prediction from the early 50s to the present time, the (unsuccessful) attempt to predict the distribution of event s throughout the solar cycle, and the shift from solar flares to coron al mass ejections as a unique parameter necessary for solar proton eve nts. Prompt, large magnitude, peak flux solar proton events are associ ated with solar activity on the western side of the solar disk; howeve r, the long duration high fluence solar proton events are associated w ith major solar activity near the central meridian of the sun that gen erates powerful interplanetary shocks which intersect the earth.