Sun Facts
Find out how big the sun is, how old it is, how it works, and many more interesting facts.
The Sun, our nearest star and the center of our solar system, is a giant burning collection of gases. Brush up on your solar facts.
A hot summer day can get anyone to start thinking about the Sun. But how much do you really know?
The Sun is the closest star to Earth and the center of our solar system. It is considered an "average" G2 star, unremarkable in the universe according to its size (1,390,000 km in diameter and 1.9x1030 kg in mass) or present age (4.5 billion years old). How hot it is depends on which part of the sun you are referring to. The interior reaches a mind-boggling 15.6 million kelvins, but the surface could be called relatively cool at 5,800 kelvins. (1 kelvin equals 1.8 degrees Fahrenheit.)
The Sun is so large it makes up more than 99 percent of our solar system's mass. The nine planets and assorted smaller bodies are all held in place around the Sun by its strong gravity. The solar system formed from a collapsing cloud of gas and dust 4.5 billion years ago, so we are now about halfway through the life cycle of our star, the Sun. Stars the sun's size follow a predictable pattern. Nuclear fusion in the sun's core converts hydrogen to helium, fueling the fire for approximately 90 percent of its life. Once all the hydrogen is used up, the sun works its way through the periodic table of elements, fusing helium into carbon and oxygen. Finally the Sun's exterior will slough off and outward, creating a planetary nebula, and all that will remain is a small core called a white dwarf.
But this is all a long time in the future, and currently the Sun is composed mostly of three-fourths hydrogen and one-fourth helium. After the energy is created in the core, it works outward from through the radiation and convection zones. The next stop outward is the surface, or photosphere. Heat and light released from the sun take eight minutes to travel from the photosphere to us, 93 million miles away on Earth.
There are thin layers above the photosphere that make up a sort of "atmosphere" on the Sun. The first is the chromosphere, and the second is the corona. The corona extends for millions of miles into space and, at 1 million kelvins, is actually hotter than the photosphere. This layer is seen as wispy white tendrils flowing from the Sun in photos of total solar eclipses.
One last interesting feature on the Sun is the sunspot. Sunspots are regions on the photosphere that are cooler than their surroundings and therefore appear darker. They rotate around the surface of the Sun as it turns on its axis, breaking apart, disappearing and reforming. It is from these regions that large explosions of gas can come hurtling off the Sun and crashing into the planets. But more about that in future articles....
The most important thought to leave you with is this: NEVER LOOK AT THE SUN WITHOUT EYE PROTECTION. Sunglasses will not do the trick. Staring at the Sun for any length of time can cause blindness. Use a filter from a reputable dealer, or visit an observatory on a public viewing day when the Sun is on the agenda.
For more on the solar system, follow the links below.
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune
