Solar cycle 24 has initially displayed much less activity than recent cycles. Based on statistical models the monthly smoothed sunspot number is likely to peak between 50 and 70 in 2013. Models based on solar polar magnetic field strength indicate the peak could occur as early as in 2012. The comparison with recent cycles is interesting to track the development of cycle 24. The X axis in the chart is the number of months since the cycle started, while the Y axis is the monthly smoothed sunspot number.
Chart color overview
Cycle Monthly smoothed sunspot number
- 21 Blue
- 22 Black
- 23 Red
- 24 Violet
- Cycle 21 started in June 1976 and lasted 10 years and 3 months.
- Cycle 22 started in September 1986 and lasted 9 years and 8 months.
- Cycle 23 started in May 1996 and lasted 12 years and 6 months.
- Cycle 24 started in December 2008.
Please note that the start dates for each cycle is calculated using the 13-month smoothed monthly mean sunspot number. One advantage of using this statistical (numerical) approach is that the start month of a solar cycle is the same as the month of the solar minimum. It is possible to use other criteria to separate solar minimum and the start of a solar sunspot cycle, however, which criteria to use and how much importance each is given, unfortunately leaves room for individual opinion.