For a larger image, click here. Joan Feynman from NASA's Jet Propulsion Laboratory developed one of the top two methods, the Australian astronomer Richard Thompson developed the other. Although each scientist took a different approach to the data and reported different results, they both looked at how the Earth's magnetic field shook during the previous solar cycle to predict the size of the next one. Scientists don't know why previous solar activity is connected to the next active period, or why the Earth's reaction to that activity helps in solar cycle prediction. But the connection allows scientists to estimate what the next solar season will bring.
Solar activity affects the Earth's magnetic field.
The new statistical model developed by Hathaway's team uses both Feynman's and Thompson's methods and integrates them with a curve-fitting technique. The curve-fitting method finds the best curve to fit recent solar activity. Based on years of observations, solar scientists have developed a library of curves that follow the average of solar cycles. By using their new prediction method, Hathaway's team can pick a curve from this library before the solar cycle even begins, and than make adjustments as the cycle progresses. For the current solar cycle, Hathaway's team predicted an average sunspot maximum of 154, with an uncertainty of plus or minus 20.