Sunspots recorded during solar cycle 15 (23 January 1923).
Sunspot data
Start date
July 1913
End date
August 1923
Duration (years)
10.1
Max count
175.7
Max count month
August 1917
Min count
2.5
Spotless days
534
Cycle chronology
Previous cycle
Solar cycle 14 (1902–1913)
Next cycle
Solar cycle 16 (1923–1933)
Solar cycle 15 was the fifteenth solar cycle since 1755, when extensive recording of solar sunspot activity began.[1][2] The solar cycle lasted 10.1 years, beginning in July 1913 and ending in August 1923. The maximum smoothed sunspot number observed during the solar cycle was 175.7 (August 1917), and the starting minimum was 2.5.[3] During the minimum transit from solar cycle 15 to 16, there were a total of 534 days with no sunspots.[4][5][6]
^Kane, R.P. (2002), "Some Implications Using the Group Sunspot Number Reconstruction", Solar Physics, 205 (2): 383–401, Bibcode:2002SoPh..205..383K, doi:10.1023/A:1014296529097, S2CID 118144552
^"The Sun: Did You Say the Sun Has Spots?". Space Today Online. Retrieved 12 August 2010.
^SIDC Monthly Smoothed Sunspot Number. "[1]"
^Spotless Days. "[2]"
^Dr. Tony Phillips (11 July 2008). "What's Wrong with the Sun? (Nothing)". NASA. Archived from the original on 14 July 2008.
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