How long is the solar cycle?

The solar cycle, also known as the sunspot cycle, is the periodic change in the sun's activity and appearance over approximately 11 years. It is caused by the periodic change in the amount of magnetic energy that is produced by the sun. This magnetic energy drives the formation of sunspots, which are dark regions on the sun's surface that are cooler than the surrounding areas.

The solar cycle is divided into two periods, called the solar maximum and the solar minimum. During the solar maximum, the number of sunspots is at its highest, and the sun emits more energy. During the solar minimum, the number of sunspots is at its lowest, and the sun emits less energy.

The length of the solar cycle can vary slightly from cycle to cycle, but the average length is about 11 years. However, there have been some cycles that were shorter or longer than 11 years. For example, the shortest solar cycle on record occurred in 1932, with a length of only 9.7 years, while the longest solar cycle on record occurred in 1793, with a length of 14.5 years.