Our Sun is an ordinary star, just one among hundreds of billions of stars in the Milky Way Galaxy. As the only star we can observe in detail, it provides a basis for our understanding of all stars. The Sun is composed almost entirely of hydrogen and helium gas.The sun's energy comes from the nuclear fusion process as it.The sun is a typical yellow dwarf; what makes it so different from all the other objects we can observe in the sky is essentially proximity. The sun is close enough to the Earth for us to view it as it truly is.These are the two basic reasons for different star colors: Temperature - cooler stars are red, warmer ones are orange through yellow and white. The hottest stars shine with blue light. Age - As a star ages it produces different chemicals which burn at different temperatures. converts hydrogen to helium. A star's color is critical in identifying the star, because it tells us the star's surface temperature in the black body radiation scale. The sun has a surface temperature of 5,500 K, typical for a yellow star. The hottest stars are blue, with their surface temperatures falling anywhere between 10,000 K and 50,000 K.Luminosity is the rate at which a star radiates energy into space. Apparent brightness is the rate at which a star's radiated energy reaches an observer on Earth. Apparent brightness depends on both luminosity and distance. Luminosity of stars is more important for us Astronomers measure a star's brightness by examining the amount of energy emitted (given off) every second. The more energy emitted, the higher the brightness. Scientists use Watts to measure energy.Once we look beyond the solar system, most of what we can learn about the Universe is based on observing stars. Not only do they light up the sky, they produce the raw materials that make life possible, and if there is life out there, it is most likely orbiting a star on its planet.
