i think an asteroid will hit the earth pretty hard.

Let worry about what's going on right now because no one can tell u how the world will end and when. Only God knows.

in 4.5 billion years the sun will enter its red giant phase and will grow in size to the point were its in our orbit ether a,b or c will happen

a we will be swallowed by the sun

b the force of gravity will push the mercy Venus earth and mars each others orbits and it would cause collisions between planets

c the force of gravity will eject the earth form the solar system

against a drunken tree

The world when end in 2012 when the great awakening will happen. We will all ascend to a higher level of conciousness and leave our physical bodies.

I'm throwing my vote for a hostile technological singularity.

Beat me to it...

I think a more thought provoking question is:

How will the universe end?

Will we burn up as the universe collapses, will we freeze as expands, or will atomic particles experience decay?

My vote is fire and brimstone. After the Rapture and Armageddon, of course.

This.

It happens with stars, and the sun is definitely a star. It's only a matter of time (still a long way away though).