太陽活動周期
Solar cycle 8 was the eighth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 9.7 years, beginning in November 1833 and ending in July 1843. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 244.9 (March 1837), and the starting minimum was 12.2.