ABSTRACT
The sun is a big ball of plasma composed primarily of hydrogen (92%), helium (8%), and small amounts of other atoms or elements. A plasma is where the electrons are separated from the nuclei because the temperature is so high (kinetic energy of nuclei and electrons is large). By the process of fusion, protons are converted into helium nuclei plus energy. The sun (Table 3.1) is a stable main sequence star with an estimated age of 4.5 * 109 years and will continue for another 4 to 5 * 109 years before starting the next phase of evolution, the burning of helium. At that point, the sun will expand and be larger than the orbit of the Earth.
