Sunspots

The region of strong magnetic field which holds the sun firmly in its place is known as sun spots. They are the cooler regions seen on the surface of the sun. Their size range from very small to large that they can be seen without telescope. It lasts for few hours for small ones and takes months time for large ones. Since they are cooler , they cannot shine as brightly as the surrounding area. Because pf this reason they appear dark. They appear gradually over the months and sometimes they cannot be seen itself. The time from minimum number of spots to minimum again is just over eleven years. This cycle is known as sunspot cycle