Chris'sPage

By Chris Thomas
 * //__Our Sun __//**

What are the Sun's structure, motion, compostion, and features? The Sun - a hot, giant ball of gas. It’s so hot, the temperature at its core is around 15 million degrees Celsius. It’s so giant, it would take 109 Earths to fit across the Sun’s disk. And yes, it is shaped like a ball and made of gas. The Sun is made of several gases, though most of it is hydrogen and helium. In fact, 99% of the Sun is hydrogen and helium - 75% is hydrogen, and 24% is helium. The other 1% consists of various gases (argon, calcium, chromium, iron, nickel, silicon, sulfur, and some others). The Sun is constantly releasing particles of these gases. This is called solar wind. Solar wind is a stream of charged particles coming from the Sun. Solar wind is incredibly powerful - traces of it were still being detected by the spacecraft //Voyager 1// in November 2003. At that time, //Voyager 1// was approximately 13.5 million kilometers away from the Sun. As previously mentioned, the core temperature of the Sun is about 15 million degrees Celsius. However, this temperature is not consistent throughout the S un. The reason for this difference is pressure. The more pressure, the more heat. Obviously, the core of the Sun is under more pressure than the surface because the Sun’s gravity is pulling everything in towards the core. So, as you move away from the core and towards the surface, the pressure and temperature decrease. The temperature on the surface of the Sun is about 6000 degrees Celsius. However, there are places on the surface where the temperature is even less than that. These places are called sunspots. A sunspot is usually around 4000 degrees Celsius. Sunspots are caused by “knots” in the Sun’s magnetic field. Because the Sun is made of gas, it’s magnetic field is not anchored to anything (unlike Earth’s, which is anchored by the solid crust). So, different parts of the Sun rotate at different speeds (the Sun rotates around its axis just like Earth). As the Sun’s magnetic field is pulled along at these different speeds, it gets “knotted.” Where a knot forms, the magnetic field is very strong, and acts like a giant hand pushing down on the Sun. This prevents hot gases from rising to the surface in that area. As a result, the area cools off and a sunspot is formed. Sometimes, the Sun’s magnetic field gets so knotted, it can’t take the pressure anymore and simply snaps. Such an event is called a solar flare. When the magnetic field snaps, large amounts of charged particles are released from the Sun and into space. Needless to say, that’s a lot of energy being released. An even more powerful solar explosion is called a coronal mass ejection. Coronal mass ejections start somewhere in the corona (upper atmosphere) of the Sun. Something (scientists aren’t sure exactly what) causes huge bubbles of magnetically charged gases to be released from the corona and into space. Incredibly huge amounts of energy (up to 10 tons of solar wind) are released during a coronal mass ejection. There are still some basic questions I have not answered yet in this report. How was the Sun formed? Why does it emit heat and light? Why do planets orbit around it? Will the Sun “die” one day? The Sun is a star like any other - it was formed by the “clumping” of gases (mostly hydrogen). Once it was big enough and dense enough, the core was under so much pressure, nuclear fusion begins. In short, the hydrogen atoms are under so much pressure, they are forced to fuse into helium atoms. This process releases a tremendous amount of energy which, once it makes its way from the core to the surface of the Sun, is released as a variety of forms: visible light, heat, UV rays, and other things. The planets orbit around the Sun because it is so massive. Everything with mass has gravity, and since the Sun is so massive, it has a lot of gravity. The gravity pulls the planets toward the Sun, but since they are traveling so fast, they stay in a consistent orbit around the Sun. One day, yes, the Sun will “burn out.” But it’s not going to happen anytime soon - experts estimate in around 4.5 billion years. Then, the Sun will run out of hydrogen to use as fuel, and begin to collapse in on itself because there is no energy pressing outward from the core to counteract the gravity pressing in. All the extra pressure on the core will start another round of nuclear reactions - this time, the helium left from the hydrogen reactions will be forced to fuse into carbon. This will cause the Sun to relase energy like never before. All the extra energy will cause the Sun to expand in size - it is now called a "red giant" star. The Sun will be so big, it will swallow the planets Mercury and Venus, and likely Earth as well. This will be an extremely unstable time for the Sun - it will release so much energy, large chunks of its atmosphere will be radiated into space. Once there is no more helium left, there will be no more energy pressing outward from the core, and the Sun will begin to collapse in on itself again. This time, however, it will not have enough mass for another round of nuclear fusion to happen. It will shrink until it is an extremely dense, glowing ball about the size of Earth. After a while, its light will fade, and it will be considered a "dead" star.

some of its features.** media type="youtube" key="lHQaELeGdyI" height="344" width="425"
 * Here is a video to help you understand the life cycle of the Sun and


 * //__WORKS CITED:__//**

Arnett, Bill. "The Sun." [] (January 25, 2009) Monday, May 25, 2009.

Freudenrich, Craig. "How the Sun Works." [] (2009) Thursday, May 28, 2009

Hamilton, Calvin. "Sun." [] (2007) Monday, May 25, 2009.

Melton-Knocke, Melanie. "From Blue Moons to Black Holes: A Basic Guide to Astronomy, Outer Space, and Space Exploration." __Prometheus Books__ (2005) Monday, May 25, 2009.

Our Sun