The number of dark sunspots is currently at its highest level in 20 years.
The number of dark sunspots is currently as high as it has been in 20 years. "We are currently at the maximum of a relatively strong solar cycle," explains solar physicist Achim Gandorfer from the Max Planck Institute for Solar System Research in Göttingen. The number of spots is dependent on solar activity, which changes within an eleven-year cycle. "Whether we are already at the end of the cycle or if there will be a further increase, cannot be said at the moment."
The spots are caused by temperature differences on the surface, as Gandorfer explains. "The sun is a layered gas ball. Energy is generated in the interior, and the hot gas rises." At the surface, the energy is radiated, and the temperature of the matter drops suddenly. "The gas then sinks back in cooler and denser form." This cycle is also known as convection.
However, it can happen that locally strengthened magnetic fields prevent the cooler gas from sinking, says Gandorfer. As a result, the cooler matter remains on the surface for a longer period. Therefore, the spots are about 4,000 degrees cooler than the surrounding surface, which is about 6,000 degrees. "The spots are still very, very hot, but they appear darker in contrast because the surroundings are even hotter and brighter."
Sunspots are a result of locally strengthened magnetic fields preventing the cooler gas from sinking, leading to their prolonged presence on the solar surface. The current high number of sunspots coincides with the maximum of a relatively strong solar cycle, indicating that we're experiencing intense solar activity.
