Things are very quiet on the surface of the Sun just now… a little too quiet. Normally, the surface of the sun is covered “sun spots,” areas of magnetic activity that are usually accompanied by flares and “coronal mass ejections,” giant streams of material that can seriously disrupt life on earth.

Lately there’s not much happening over on good old Sol. For the past few years we’ve been in a “solar minimum”—a period of reduced activity. Most people expected that the minimum would end last year, but it seems to be stretching on longer than expected.

Now a group of scientists at the National Solar Observatory in Tucson, Arizona think that they’ve finally figured out why. Using long-term observations from the Global Oscillation Network Group (GONG) facility, the team was able to watch an east-to-west jet stream some 1,000-7,000 km below the sun’s surface. They presented their results at the Solar Physics Division meeting of the American Astronomical Society.

The jet stream has moved sluggishly from the polar regions of the sun to the equator, and that’s delayed the onset of the latest solar cycle. Soon however that may all change—the scientists believe that the jet stream has reached a critical point where it can rekindle sunspots and start the cycle anew. So keep an eye on our nearest star, but please remember not to stare at the Sun directly.

Image: SOHO/Nasa