NASA, NOAA: Sun Reaches Maximum Phase in 11-Year Solar Cycle – NASA Science

Sunspot number over the previous 24 solar cycles. Scientists use sunspots to track solar cycle progress; the dark spots are associated with solar activity, often as the origins for giant explosions — such as solar flares or coronal mass ejections — which can spew light, energy, and solar material out into space.

For these images and more relating to solar maximum, visit https://svs.gsfc.nasa.gov/14683.