What are Sunspots?

A sunspot is a relatively cooler region on the surface of the sun. For an observer on earth, sunspots appear as dark patches on the bright face of the sun. The number and size of sunspots on the sun’s surface keep changing. However, their numbers peak once in about eleven years. The peak-period during which the number of sunspots is very high is called the sunspot-maximum.

Sunspots are believed to be caused by the intense magnetic activity at the sun’s surface which prevents the hot-fluid of the star’s interior from rising to the surface. Thus the surface remains ‘cool’ and ‘dark’. When sunspots occur in large numbers, magnetic disturbances such as occurrence of northern lights or disturbances in the transmission of radio-waves are observed on earth.