The sun is approximately 877,000 miles in diameter, making it the biggest object in the Solar system.
The sun is essentially a big ball of gas, made up of 70% hydrogen and 28% helium. The remaining 2% is made up of metals. But these percentages change over time as the sun converts hydrogen to helium. This conversion happens at the sun’s core. The temperature at teh core is about 15,000,000 Kelvin. (Kelvin is a unit of temperature in which zero occurs at absolute zero.) This intense heat is generated by nuclear fusion, the conversion of hydrogen to helium.
The nuclear fusion generates about 386 billion billion megawatts of energy. Now that’s solar power.
The energy travels from the dense core to the surface of the sun, along the way losing heat. By the time it reaches the sun’s surface it is in the form of visible light. The surface of the sun is called the photosphere. With a temperature of about 5800 Kelvin, it is considerably cooler than the raging hot core. Just above the photosphere is the chromosphere. Above this layer, and extending millions of kilometers into space is the corona. The corona is only visible during a total solar eclipse.
The average distance between the Earth and the sun is about 93,000,000 miles. The light from the sun takes about eight and 1/2 minutes to travel that distance. Not only is the sun generating heat and light, it is also generating solar winds. Made up of mostly electrons and protons, the solar winds blow through the Solar system at about 450 kilometers per second.
Solar winds are not completely understood, but it is believed they have a direct relationship with certain events such as the Northern Lights, and geomagnetic storms. These storms can knock out power grids on the planet Earth. During such a storm, a solar wind shock wave strikes the Earth’s magnetic field and entire regions, such as the United States west coast, loses power. It is, of course, more complicated than that, but the exact process is still part speculation. It is understood, though, to be a cause and effect event.
The sun is old, really old by human standards, with an approximate age of four and 1/2 billion years. It has a life expectancy of about nine or ten billion years, so it has reached middle age.
What will happen when the sun dies? The sun will die when it has burned up all the hydrogen at its core. The core then begins to shrink, and the helium will convert to carbon. The outer layers swell, and the surface cools. It is now a Red Giant, glowing red and swelling up.
The outer layers of the star will then peel off or eject outward, resulting in a planetary nebula. The nebula is a shell made up of the hot gas that has been expelled from the dying star. All that will be left is a small, shrinking bit of core, called a Remnant. Eventually it will be a very small star known as a White Dwarf, surrounded by nebula.
In the meantime, the sun will continue to shine for many, many centuries, sending fresh new light to the Earth every eight and 1/2 minutes, generating billions of megawatts of energy, and sending shock waves of solar winds to knock out the grids of artificial power here on Earth.
1)http://seds.lpl.arizona.edu/nineplanets/nineplanets/sol.html
2)http://www-istp.gsfc.nasa.gov/istp/outreach/workshop/thompson/facts.html
