On the photosphere of the Sun it can be observed groups of dark spots. These dark spots are called sunspots and are temporarily, during from a few days to a few months. Sunspots are observed as dark compared to the surrounding areas because of the low temperature compared to the rest of the photosphere. The reduced temperature at the sunspots is due to high magnetic fields that counteract the convection preventing hotter material to reach the surface.\par
The sunspots can be seen with the naked eye and the first records of sunspots are dated back to 800 B.C made by Chinese astronomers \cite{HSO}, while the first European records where done by Galileo Galilei and Thomas Harriot in 1610 by using a new telescope. In 1849 continuous daily observations
The sunspots can be seen with the naked eye and the first records of sunspots are dated back to 800 B.C made by Chinese astronomers \cite{HSO}, while the first European records where done by Galileo Galilei and Thomas Harriot in 1610 by using a new telescope. In 1849 continuous daily observations