The sun is important to earth because life could not survive without the sun. It delivers 99% of the energy and the sunlight which the earth uses. The sun is the main source of energy, prividing the life and energy on earth. The solar energy and photosynthesis drives life to reverse entropy, the reason that makes the plants and leaves green. If the sun had never existed, the earth would have never been able to support life. Ths sun is the key factor to life. It may affect the earth both positively and negatively.