Solar cycle 17

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Solar cycle 17
Sunspot Data
Start date September 1933
End date February 1944
Duration (years) 10.4
Max count 119.2
Max count month April 1937
Min count 7.7
Spotless days 269
Cycle chronology
Previous cycle Solar cycle 16 (1923-1933)
Next cycle Solar cycle 18 (1944-1954)

Solar cycle 17 was the seventeenth solar cycle since 1755, when extensive recording of solar sunspot activity began.[1][2] The solar cycle lasted 10.4 years, beginning in September 1933 and ending in February 1944. The maximum smoothed sunspot number (monthly number of sunspots averaged over a twelve-month period) observed during the solar cycle was 119.2 (April 1937), and the minimum was 7.7.[3] There were a total of 269 days with no sunspots during this cycle.[4][5][6] A great aurora display was seen all over Europe on 25 January 1938, as far south as Portugal and Sicily, frightening many people. Some thought that the red glow indicated large fires, while others linked it to the Fátima prophecies. An aurora was visible over New York on 3 April 1940.[7]

See also[edit]


  1. ^ Kane, R.P. (2002). "Some Implications Using the Group Sunspot Number Reconstruction". Solar Physics 205(2), 383-401.
  2. ^ "The Sun: Did You Say the Sun Has Spots?". Space Today Online. Retrieved 12 August 2010. 
  3. ^ SIDC Monthly Smoothed Sunspot Number. "[1]"
  4. ^ Spotless Days. "[2]"
  5. ^ What's Wrong with the Sun? (Nothing) more information: Spotless Days. "[3]"
  6. ^ Solaemon's Spotless Days Page. "[4]"
  7. ^