The Sun is a star of spectral type G2V with a surface temperature of 5500 ° C, its equatorial diameter is 1.391 million km (approximately 109 times the Earth's diameter) which translates into angular size of 31 arc minutes (on average ) for an observer located on Earth, with a visual magnitude of -26.7. As its surface is not solid its period of rotation differs from 26,8 days in the equatorial region to 36 days in the polar regions. The solar activity is characterized by a cycle of 11 years which is measured between two minimum periods where sunspots are virtually nonexistent and that has at its midpoint a peak of activity where sunspots are very abundant and often large, these spots are areas of high magnetic intensity where convection is virtually nullified thereby reducing the amount of energy transported from the interior of the sun, therefore those areas are much cooler assuming a darker appearance with respect to the surrounding area.
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