solar cycle

400 years of sunspot history, including the Maunder Minimum "The prediction for solar cycle 24 gave a smoothed sunspot number maximum of about 101 in the late 2013. The smoothed sunspot number reached 116.4 in April 2014. This will probably become the official maximum. This second peak surpassed the level of the first peak (98.3 in March 2012). Many cycles are double peaked but this is the first in which the second peak in sunspot number was larger than the first. We are currently over seven years into cycle 24. The predicted and observed size made this the smallest sunspot cycle since cycle 14, which had a maximum smoothed number of 107.2 in February of 1906."

The Solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surface. Over the period of a solar cycle, levels of solar radiation and ejection of solar material, the number and size of sunspots, solar flares, and coronal loops all exhibit a synchronized fluctuation from a period of minimum activity to a period of a maximum activity back to a period of minimum activity.