The Sun is the star at the center of the Solar System. It is by far the most important source of energy for life on Earth. The Sun is a nearly spherical ball of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. The diameter of the Sun is about 109 times that of Earth, and it has a mass about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System.[14] Chemically, about three quarters of the Sun's mass consists of hydrogen, whereas the rest is mostly helium, and much smaller quantities of heavier elements, including oxygen, carbon, neon and iron.