(ORDO NEWS) — Sunspots are areas on the surface of the Sun that appear darker than the surrounding area. They are caused by the Sun’s massive magnetic field curling up and breaking through the surface. Sunspots come and go according to an 11-year cycle that tracks the Sun’s magnetic activity.
Astronomers have known about sunspots since ancient times, although they were difficult to observe before the invention of the telescope. Galileo Galilei made many observations of them and used their movement to prove that the Sun rotates.
One sunspot lives from several days to several months. But they rarely appear alone, almost always appear in groups.
A group on one half (northern or south of the equator) of the Sun usually finds a similar group on the opposite side. Such groups exist up to several months. After several years of intense sunspot activity, they begin to decrease. Sometimes the Sun remains free of sunspots for many years before they reappear.
For centuries, astronomers have recorded a regular 11-year disappearance and reappearance of sunspots. Through careful observations, measurements and laboratory experiments, astrophysicists have established that the activity of these spots is associated with the magnetic field of the Sun.
When the magnetic field is weak and entangled, there are few spots. Over time, the Sun’s rotation entangles the magnetic field lines, causing them to erupt from the surface like worms popping out of a rotten apple. Spots appear where field lines exist and come to the surface.
Sunspots appear darker because they are colder than the surrounding surface, typically by several thousand Kelvin. Strong magnetic fields at the spots interfere with the normal heat convection cycles near the surface, causing a cooling effect.
Other stars also have their own spots, in which case astronomers call them star spots.
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