Keith Strong and Julia Saba
NASA Goddard Space Flight Center and Univ. of Maryland Astronomy Dept.
The Solar Cycle Conundrum
We have known for 170 years that sunspots come and go on a roughly 11-year timescale. Despite many efforts to develop empirical or physical models of the solar cycle, we have failed to find a method of predicting the timing or amplitude of an upcoming solar cycle with any degree of confidence. While this was once considered an interesting intellectual exercise to test how well we understood the inner workings of the Sun, it now has become an important economic issue as our dependence on space technology increases. The vulnerability of over $1T in space assets to space weather effects increases with the solar activity levels that are driven by the solar cycle.
The Sun is a magnetic variable star so we will look at the basic characteristics of the solar dynamo that have to be reproduced by any viable solar cycle model. Then we will briefly discuss some of the techniques used to predict solar activity and see how well they have done so far in predicting the current solar cycle. Using extended observations of the Sun’s magnetic field from SOHO and various ground-based observatories in conjunction with coronal imaging has led us to find some new patterns in solar activity that have shown promise in predicting certain aspects of the solar cycle.