About the Sun?

There has about 5 billion years of hydrogen fuel left in core, it's a fission reaction not chemical and when it runs out of hydrogen it will collapse a bit, heat up and start burning helium which will create more radiation pressure expanding the outer layers to a red giant. The sun will eventually blow off these outer layers and become a dim white dwarf. It is not massive enough to become a super nova or black hole.

Only the surface is burning.

Below the surface is a molten mass of liquid gases that are so

dense that they have become metallic in nature. That is a gas form quite unlike anything here on Earth, and dense beyond

anything we can comprehend. So, it will burn, and burn, and

continue to burn for maybe a billion more years.

Sun contains huge content of gas called 'Hydrogen'. Unlike Earth, it does not contain any rock, all it contain is Gas. It consumes around 4 million tonnes of hydrogen every second. Due to chemical reactions, hydrogen gets fused in Helium which produces heat. Renewal of fuel is not possible. However, sun's Hydrogen will exhaust after 5000 crore years (As far as I remember from my school studies) from now. Upon exhaustion, it will get converted to what is called a 'Black Hole' with so high gravititional force, that it will engulf every planet in our solar system. Even light can't escape a Black Hole!!

in 5000 million years time something might happen to stop the sun releasing energy, when the supply of hydrogen runs low, things will re-arrange themselves, and the earth might be destroyed during this time.

At the sun's core, the temperature is fantastically high, and 4 nuclei (parts) of hydrogen make one nuclei (part )of helium. This causes energy to be released every time it happens, and a little mass is also lost, - about 4,000,000 tons of waste per second - but because of the great mass of the sun ( equivalent to 333,000 bodies each the mass of the earth ) it goes unnoticed in our terms of a time period.

there is nucleous rection takes place which is called as nuclear fission in which four hydrogen atom joins and make one hellium atom. the mass of one hellium particle is less then the sum of four hydrogen atoms, so the rest of mass is converted into energy according to einsteins equation e=mc2,after billion years when hydrogen will be over then sun will not burn and wil be converted into red gaint star.

it will burn eventually, probably a billion years or so.. you know, stars burn out probably every day in the universe...and the sun is a star just like any other one

it will burn out in about 1 billon years,but scientists also said the world will expolde in 2012