Context

Sunspots are temporary phenomena on the Sun's photosphere that appear as spots darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection. Sunspots usually appear in pairs of opposite magnetic polarity. Their number varies according to the approximately 11-year solar cycle.

Source: https://en.wikipedia.org/wiki/Sunspot

Content :

Monthly Mean Total Sunspot Number, from 1749/01/01 to 2017/08/31

Acknowledgements :

SIDC and Quandl.

Database from SIDC - Solar Influences Data Analysis Center - the solar physics research department of the Royal Observatory of Belgium. SIDC website