Our solar system is composed of the Sun and all things which orbit around it: the Earth, the other 
nine planets, asteroids, and comets. The Sun is 93 million miles away from the Earth (this 
distance varies slightly throughout the year, because the Earth's orbit is an ellipse and not a 
perfect circle).

The Sun is an average star, in that there are other stars which are much hotter or much cooler, 
and intrinsically much brighter or fainter. However, since it is by far the closest star to the Earth, it 
looks bigger and brighter in our sky than any other star. With a diameter of about 870,000 miles it 
would take 110 Earths strung together to be as long as the diameter of the Sun.  

The Sun is mostly made up of hydrogen (about 92.1% of the number of atoms, 75% of the mass). 
Helium can also be found in the Sun (7.8% of the number of atoms and 25% of the mass). The 
other 0.1% is made up of heavier elements, mainly carbon, nitrogen, oxygen, neon, magnesium, 
silicon and iron. The Sun is neither a solid nor a gas but is actually plasma. This plasma is 
tenuous and gaseous near the surface, but gets denser down towards the Sun's fusion core.