Solar cycle 17

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 (SIDC formula) observed during the solar cycle was 198.6 (April 1937), and the starting minimum was 5.8.[3] During the minimum transit from solar cycle 17 to 18, there were a total of 269 days with no sunspots.[4][5][6]

Solar cycle 17
Sunspot data
Start date	September 1933
End date	February 1944
Duration (years)	10.4
Max count	198.6
Max count month	April 1937
Min count	5.8
Spotless days	269
Cycle chronology
Previous cycle	Solar cycle 16 (1923–1933)
Next cycle	Solar cycle 18 (1944–1954)

History

1938

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

• List of solar cycles

References

1. 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
2. "The Sun: Did You Say the Sun Has Spots?". Space Today Online. Retrieved 12 August 2010.
3. SIDC Monthly Smoothed Sunspot Number. ""
4. Spotless Days. ""
5. Dr. Tony Phillips (11 July 2008). "What's Wrong with the Sun? (Nothing)". NASA.
6. Solaemon's Spotless Days Page. ""
7. Storms, Solar (28 July 2017). "Space Weather Newspaper Archives". www.solarstorms.org.