The main source of energy for the planet is the sun. Solar energy includes light, radio waves and X-rays, all of which provide energy on Earth.
Solar energy is a key element of photosynthesis, which is the process that green plants use to make food and grow. Photosynthesis creates Earth's energy as plants capture the sun's light and turn it into sugar. Plants then provide energy for animals by functioning as a food source. Photosynthesis also provides most of the oxygen that animals and humans need to breathe. Light absorbed by Earth heats the land surfaces, the oceans and the atmosphere.