Role of Sun in the origin and evolution of life on earth:
The Sun played a very vital role in the origin of life and its evolution on earth as is evident from the following-
In the initial stages of the origin of life on earth, the chemicals such as carbon, hydrogen, oxygen and nitrogen present in the earth’s atmosphere combined to form complex organic compounds under the influence from the Sun’s high energy radiations which further gave rise to larger molecules like hydrocarbons, simple sugars, fatty acids, amino acids, proteins etc.
The earliest organisms were heterotrophs but, when chlorophyll molecules were formed, some of the organisms became autotrophs. The autotrophs started manufacturing their organic food material from the raw materials in the presence of sunlight.
In fact, the sun acted as the only source of energy for the entire living world. Because it is in the presence of sunlight that the plants are able to manufacture their food. The green chlorophyll has the unique ability to trap solar energy. On this food (containing energy from the sun) trapped by the green plants depends the entire, living world, because all organisms whether herbivorous animals or carnivorous animals depend directly or indirectly on the sun.
If the sun was not there, organic evolution would not have taken place, because in the absence of photosynthesis no food would have been made available on the earth. Moreover, it is during the photosynthesis that the green plants give out the oxygen which is utilized by the animals.
So, the Sun played a very significant role in the origin and evolution of life.