Answer the following question.
why do stars evolve ?
Star loses its energy constantly due to continuous emission of light and energy. This means that the temperature of a star decreases continuously and hence its gas pressure which thereby decreases its stability. But we know a star is very stable. So, to maintain the stability of a star, its temperature is maintained constant with the help of energy released by the burning of fuel at its centre. This burning and therefore the decrease in the amount of fuel is the reason for the evolution in the stars.