päikeselõkete

Päikeselõkete, also known as sunspots, are temporary phenomena on the photosphere of the Sun that appear as darker spots than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection.

The existence of sunspots was first observed centuries ago, but their systematic study began with the invention of the telescope. Galileo Galilei was one of the first to observe and record sunspots in detail. He noticed that they moved across the solar disk, providing evidence that the Sun was rotating.

Sunspots are not static; they can appear, grow, shrink, and disappear over periods ranging from days to weeks. They often appear in pairs or groups, with complex magnetic field configurations. The number of sunspots visible on the Sun varies in an approximately 11-year cycle, known as the solar cycle. At the peak of the solar cycle, there are many sunspots, while at the minimum, the Sun may appear almost spotless.

The darker appearance of sunspots is due to their lower temperature compared to the surrounding photosphere. While the photosphere is around 5,778 Kelvin, sunspots are typically around 3,000 to 4,500 Kelvin. This temperature difference is significant enough to make them appear dark against the bright solar surface.

Sunspots are also associated with increased solar activity, such as solar flares and coronal mass ejections. These events can have significant effects on Earth, including disruptions to satellite communications, power grids, and radio transmissions. Studying sunspots helps scientists understand the Sun's magnetic activity and its influence on space weather.