Solar cycle 17

Solar cycle 17 was the seventeenth solar cycle since 1755, when extensive recording of solar sunspot activity began. 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. There were a total of 269 days with no sunspots during this cycle. 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.