Energetic particles from the Sun have only been studied in detailduring the last three decades. The modern record is good, although thenumber of the largest solar particle events are very few. The nuclidesmade by solar energetic particles in lunar rocks have been used toextend the record of these particles back ~107 years. Themodern and ancient records are similar. By combining both sets of data,it has been inferred that solar particle events much larger than thelargest events observed during the last four solar cycles are very rare
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