päikeselaike

Päikeselaike, often translated as sunspots, are temporary phenomena on the photosphere of the Sun that appear visibly darker than surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection. The temperature within a sunspot is typically around 3,000 to 4,500 Kelvin (2,700 to 4,200 degrees Celsius), whereas the photosphere's temperature is about 5,800 Kelvin (5,500 degrees Celsius). This difference in temperature makes them appear dark by contrast.

Sunspots are not static; they can grow, shrink, and change shape over periods of days to weeks. They often appear in pairs or groups with opposite magnetic polarities. The number of sunspots observed on the Sun varies in an approximately 11-year cycle, known as the solar cycle. This cycle influences solar activity, including solar flares and coronal mass ejections, which can have effects on Earth's technological systems and space weather.

The study of sunspots has a long history, dating back to ancient observations, though their true nature was only understood with the advent of telescopes. Galileo Galilei's detailed observations in the early 17th century were crucial in establishing their existence and variability. Sunspots are a key indicator of the Sun's magnetic activity and play a significant role in understanding solar physics and its influence on the heliosphere.