The approximately 11-year period during which the frequency and number of Sunspots, coronal mass ejections, solar flares, and other solar activity rises and falls. Also called the Sunspot cycle
Space Science Institute (SSI),Space Weather Center, Glossary of Space Weather-Related Terms, Colorado, USA 2011. http://www.spaceweathercenter.org/glossary/001/01. html, (Space Wthr - Amer) {860}