How do stars evolve and die?
• What are the interesting features of stars? • What are the physical and chemical data for stars? Material present in the forms of stars, constellations, galaxies, solar systems, planets, nova, quasars, neutrons stars, comets, interstellar dust, asteroids, and supernova in the unlimited space we call universe or sky, had fascinated Kepler, Galileo, Descartes, Newton and many others. Their revelations have made the universe less mysterious. Distances between stars and planets and their masses are usually expressed in astronomical units such as light years (nine and half trillion kilometers, 9.5×1012 km), mass of the sun (1.989×1030 kg), and the mass of the earth (six heptillion kilograms, 5.976×1024 kg). There are billions of stars out there in the sky, but only a small percentage of them are visible to the unaided eyes. The sun is one of them. The next nearest star, the Alpha or Proxima Centauri is 4.3 light years from the Sun, whereas the Sirius and the Procyon are 8.6 and 11.4 light
