How many sunspots were recorded in 1990?
The following is from the source listed belowT he “sunspot number” is then given by the sum of the number of individual sunspots and ten times the number of groups. Since most sunspot groups have, on average, about ten spots, this formula for counting sunspots gives reliable numbers even when the observing conditions are less than ideal and small spots are hard to see. an approximate The following is the sunspot number(SSN) updated month for 1990 Year mo SSN DEV 1990 01 177.3 27.9 1990 02 130.5 62.5 1990 03 140.3 47.8 1990 04 140.3 42.2 1990 05 132.2 37.2 1990 06 105.4 39.6 1990 07 149.4 59.6 1990 08 200.3 57.0 1990 09 125.2 21.8 1990 10 145.5 38.1 1990 11 131.4 35.6 1990 12 129.7 32.
