太陽活動周期
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 observed during the solar cycle was 234.0 (August 1870), and the starting minimum was 9.9. During the minimum transit from solar cycle 11 to 12, there were a total of 1028 days with no sunspots (the highest recorded of any cycle transit to date).