Our Sun is a very ordinary star in mass and temperature. The Sun and its planets (and regardless of what you may have read or heard, our Solar System has nine planets, including Pluto) formed about four and a half billion years ago from a cloud of (mostly hydrogen) gas and fine dust that was perturbed somehow—perhaps by the gravity of a passing star, perhaps by pressure waves from the explosion of a massive star in the neighborhood. Whatever the cause, the gas and dust in the cloud began to clump together. Once that process began, the equilibrium of the cloud was upset and the denser areas attracted more and more gas as their increased mass exerted a greater gravitational attraction on the cloud. When the cloud reached a certain density it had to—according to the theory of gravity—take the spherical shape that virtually all celestial bodies above a certain mass have. As such a sphere—it is now the Proto Sun—gains more and more mass the gravitational pressure on the hydrogen at its center causes the core to become very hot. Finally, when the temperature is above about 10 million Kelvins, the hydrogen atoms at the core are moving with such energy that when they collide they fuse together to make helium. A star is born. The fusion process produces more energy than is required to fuse hydrogen into helium, and the excess energy travels to the surface of the star and into space as stellar radiation. Amazingly, the complex process of convection that carries radiation from the Sun’s core to its surface requires millions of years to transport the radiation from the core to the surface. Then it takes another eight minutes to reach the Earth. Now it is the sunshine that makes life on Earth possible. (Though it is also the ultraviolet radiation that may cause skin cancer and it is the powerful radiation that may damage earth satelittes, disrupt radio and television signals, and temporarily shut down electric power distribution systems on Earth.) The larger a star is, the faster it burns its fuel; some massive stars live only some few millions of years before they exhaust the supply of fuel they require for fusion and with no radiation pressure to maintain their size, they collapse on themselves in a Supernova explosion. Our Sun is a relatively small star, and it burns its fuel at a much more economical rate. The Sun has now burned about half of its fuel, and it is expected to last for another five billion years or so (so you can proceed with your plans for the weekend). The Sun is the subject of intense scientific exploration, especially from spacecraft. NASA maintains many web pages that contain good science presented in such a way that laymen like you and me can understand it. Here is a starting point for basic facts about the Sun.