SP-402 A New Sun: The Solar Results
THE SUNSPOT CYCLE, 1610-1976. Sunspots
come and go on the Sun in an irregular cycle of about 11 years, with
some obvious long-term changes. Annual mean sunspot numbers (an
average measure of spottedness of the Sun) are shown here for each
year since the discovery of the telescope. Data on the earlier parts
of the graph are less reliable than in later periods.
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