Explained: The Sun

The Sun is a star located at the center of our solar system. The sun itself makes up 99.8% of our solar system's mass. The eight planets, three dwarf planets, and numerous other objects such as asteroids and comets orbit the sun. The Sun consists of mostly hydrogen and helium, which it uses as fuel to keep burning.



Currently, the Sun is 4.5 billion years old. When the Sun is 10 billion years old, it will expand to become a red giant. When is becomes red giant, it will be 2,000 times larger and 100 times brighter. Mercury and Venus will become engulfed by this growing Sun, but recent scientific models suggest that the Earth will be spared this awful fate and will move out to a farther orbit.

Since the Sun not a very large star, it will not die in the very large explosions known as a supernova. Instead, the Sun will slowly shed its outer layers which will become the beginnings of a planetary nebula (a cloud of gas). Then only the Sun's core will remain as a white dwarf. This white dwarf will be dramatically smaller than the current size of the sun, and will remain in space with just a white glow. This white dwarf will continue to glow for billions of years; all the while slowly becoming fainter.

The graphic below illustrates the Sun's size when it becomes a red giant.

An example of a planetary nebula is the Eskimo Nebula (NGC 2392). As you can see, the gas surrounds the white dwarf which is located in the center of the image. The white dwarf illuminates the nebula and gives it its beauty.

Image Credits: NASA, SPACE.com, Astronomy Picture of the Day (APOD)\

Alternate Article: The Sun's History & Future