Solar cycle 19

Solar cycle 19 was the nineteenth solar cycle since 1755, when extensive recording of solar sunspot activity began.^[1][2] The solar cycle lasted 10.5 years, beginning in April 1954 and ending in October 1964. The International Geophysical Year occurred at the peak of this solar cycle.

Solar cycle 19
A solar prominence during solar cycle 19 (11 April 1959).
Sunspot data
Start date	April 1954
End date	October 1964
Duration (years)	10.5
Max count	285.0
Max count month	March 1958
Min count	5.1
Spotless days	227
Cycle chronology
Previous cycle	Solar cycle 18 (1944–1954)
Next cycle	Solar cycle 20 (1964–1976)

The maximum smoothed sunspot number observed during the solar cycle was 285.0, in March 1958 (the highest on record^[3]), and the starting minimum was 5.1.^[4]

During the minimum transit from solar cycle 19 to 20, there were a total of 227 days with no sunspots. This was the lowest number since 1850.^[5][6][7]

Extreme events

A geomagnetic storm in February 1956 interfered with radio communications and prompted a search for the British submarine Acheron after it lost radio contact.^[8]

Intense red aurora displays frightened people in Europe on 11 February 1958 and were visible from many US cities as far south as the 40th parallel. This geomagnetic storm caused a radio blackout over North America.

Aurora displays were visible over New York on 13 November 1960 and 1 October 1961.^[9]

See also

• List of solar cycles