This period is known as the solar cycle, and it's marked by a variety of changes in solar activity, including:

* Sunspot number: The number of sunspots on the Sun's surface peaks and troughs during the cycle.

* Solar flares: Powerful bursts of energy released from the Sun are more frequent during the solar maximum.

* Coronal mass ejections (CMEs): Large expulsions of plasma and magnetic field from the Sun's corona are more common during the solar maximum.

While the average solar cycle is about 11 years, individual cycles can range from about 9 to 14 years.