Sunlight and Stars

Science of the Sunlight and Stars

University of Phoenix
January 14, 2008

Science of the Sunlight and Stars
The Milky Way Galaxy has over 100 billion stars. The Sun is the largest star in the Milky Way located about 28,000 light-years from the galactic center. Astronomers have been able to learn more about the attributes of the Sun in the recent twentieth century. They have been able to determine through radioactive dating of the Earth, Moon, and meteorites that the Sun, a G-2 V. type star, has been shinning for almost five billion years. The Sun, which contains more that 99.9% of the solar systems mass, is not a solid object even though on the surface it appears as one. Compared to Earth, the sun is about 333,000 times the mass and is almost 10 times the size of Jupiter. Because the Sun has so much mass it is able to produce its own light. In fact, almost all the visible light that is received in space comes from hot objects like the Sun and the stars.
Internal Structure
Before the twentieth century astronomers were able to determine the density and temperature structure of the interior of stars through principles of gas physics but they did not know where the energy of the Sun came from and how energy is produced. Helping to unlock this secret, scientists have studied the interior structure of the Sun. The Sun is gaseous - made up of mostly hydrogen and helium. Deep in the center of the Sun is the solar core. The core makes up about 10% of the mass of the Sun. Temperatures are extreme in the core with internal temperatures around15 million Kelvin (K). The core is very dense – “more than 100 times that of water and the pressure is 200 billion times that on the surface of Earth” (Bennett, Donahue, Schneider & Voit, 2007, p. 482). The extreme heat in the core produces nuclear reactions where hydrogen gases are turned into helium. As this energy moves outward on its way to the surface it enters the radiative zone.
The radiative zone is an area of the...