PRB_Ohio writes "The sun is in the middle of a century long solar minimum, and sunspots have been puzzlingly scarce for more than two years. Now, for the first time, solar physicists might understand why. The gist is that there is a 'jet stream' like phenomenon about 7,000km below the surface of the sun. The streams migrate slowly from the poles to the equator and when a jet stream reaches the critical latitude of 22 degrees, new-cycle sunspots begin to appear. Scientists at the National Solar Observatory (NSO) in Tucson, Arizona, used a technique called helioseismology to track and analyze the streams."