|XRT Mission Ops
The current solar cycle, the 24th since sunspot monitoring began in earnest around 1755, has peaked and is moving into its declining phase. An image for every year is displayed above, starting in 2008, which heralded the new cycle with the appearance of the first reversed-polarity sunspot. This cycle is notable for having the lowest activity levels since the dawn of the space age and the lowest sunspot counts in a century. The roughly 11-year sunspot cycle is a product of the solar dynamo that generates the Sun's magnetic field. We understand the dynamo to be caused by the motions of charged particles swirling around the interior, and we understand that surface activity develops as the magnetic field is graudaually tangled by differential rotation. But what causes this particular cyclic activity pattern, cycle-to-cycle variations, and the changing distribution of active regions throughout the cycle are open questions. A movie showing the progression from 2007 to 2013 is available here.
Keywords: Solar Cycle, Full Disk