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March 2017 Solar Activity Resembles Dalton Minimum: Weakest Month Recorded! | Principia Scientific Intl.
Our source of energy continued to be especially quiet last month. The mean sunspot number (SSN) was 17.7 and the sun was completely blank for 16 days. It is important to recall once again that the SSN is not simply the sum of the observed sunspots, rather it is generated by the number of spots multiplied by the 10-fold of the observed sunspot regions. When one single spot is observed in an active region, this yields an SSN of 11.