Solar cycle 11 was the eleventh solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 11.8 years, beginning in March 1867 and ending in December 1878. The maximum smoothed sunspot number (monthly number of sunspots averaged over a twelve-month period) observed during the solar cycle was 140.3 (August 1870), and the minimum was 2.2. There were a total of approximately 1028 days with no sunspots during this cycle (the highest recorded of any cycle to date).
Strong auroral displays were observed in October 1870, February 1872, and August 1872.