What are the sunspots?

 What are the sunspots? 

           The most spectacular feature of the Sun's surface is the 'sunspots'. Galileo was the first man to observe these spots in 1610 A.D. with the help of his telescope. Through the telescope, the sunspots appeared like dark holes on the shining surface of the Sun. 

           These spots often appear in groups. They increase in number and then diminish in regular cycles. These cycles repeat every 7th, 11th or 14th year. The portion of the Sun having these spots emits light having lower intensity. According to modern scientific theories, these spots are formed by reactions between the electrically charged gases of the Sun and solar magnetic fields. When at any point on the Sun's surface, strong magnetic field develops, the temperature of that place is lowered. Consequently, these portions appear as black spots amidst hotter and brighter portions. The temperature of these spots is estimated to be around 4000°C. They are not permanent in nature but go on changing.

            Can you guess what is the size of these spots? Some spots are big enough to accommodate hundreds of earth's. Even a small spot is so big that is can cover two thousandth part of the Sun's surface. These spots are spread over an area of 500 million square miles on the Sun. On June 4, 1946, scientists saw a sunspot measuring 4,80,000 kilometres in length and 1,12,000 kilometres in breadth. Most of the solar spots last for a few days, but some may last for two months or even more. 

            It is inferred from the change of state of sunspots that, like the Earth, the Sun is also rotating on its own axis. These spots are seen moving from east to west since the Sun is also presumed to be rotating from east to west.