The surface of the sun is speckled with dark blemishes called sunspots. These cooler areas can last from a few days to a few months, and result from the interaction of the sun’s convecting gases with the magnetic fields they generate. Where the magnetic fields are particularly strong, they prevent some of the sun’s heat rising to the surface, creating a sunspot. Sunspots were noted by Chinese and Ancient Greek astronomers, observed telescopically by Galileo and can be seen with the naked eye (by those foolish enough to look).
It is remarkable that a system as turbulent as the sun produces such regular magnetic activity: the number of sunspots peaks and troughs according to an 11-year cycle. The Cambridge professor Nigel Weiss studied the causes