THE SUN

There are about 100 billion stars in our galaxy and out of them our sun is the closest. With a diameter of 1,390,000 kilometers it is also the largest and therefore the hottest even though it is only a yellow star. The mass of the sun is 1.989e30 kilograms and the temperature is 5800 Kelvin on the surface, which is called the photosphere as well as the chromospere, which is a small region right above the photosphere. There is also a layer above the chromosphere called the corona layer, which has a temperature of 1,000,000 Kelvin. This layer extends millions of kilometers into space, but can only be seen during a solar eclipse. The temperature on the core is 15,600,000, which is way more than the surface. This is because each second about 700,000,000 tons of hydrogen are converted into about 695,000,000 tons of helium and 5,000,000 tons of energy in the form of gamma rays. But by the time that these gases reach the surface they would've cooled down and become only visible light. In spite of that the amount of output is still humongous and is produced by nuclear fusion reactions. The sun also emits solar winds, which are a low-density stream of charged particles, which mostly contain electrons and protons. Unlike the Earth the sun is not a solid body, instead it's a planet made up of gases. In addition, hundreds of sunspots lie on the sun. These areas are "cool" regions and only 3800 Kelvin. They can be as big as 50,000 km. in diameter. These sunspots are created by complicated interactions with the suns' magnetic field. Occasionally spectacular loops and prominences are visible along with solar flares. They can rise hundreds of kilometers high and are huge. One day the sun will become a black hole or at least die and make the world cold and dark. Unless we find a solution humans will probably become extinct just like dinosaurs. But don't worry our sun has lived for 4.5 billion years until now and will live for another 5 billion years. So we're safe for now!!!

http://www.nineplanets.org/sol.html