First of all the sun idea is out of the question; Im sorry but I have to do this.
Let's go through the phases of a star. The first phase would be the protostar when the star in human comparisons would just be a fetus, the second would be the intial fusion ignition when the star would just be a infant/teenager, the third phase would be the main sequence when the star is a adult (that is the state in which our sun is in right now), the fourth phase is when the star becomes a red giant/supergiant, now it is in it's middle age (by this time the human race is extinct and has been extinct for a long time), the fifth phase is when the star becomes a white dwarf, it is now a old person and lastly the sixth phase is when the star becomes a black hole, the star has died and is consuming up the solar system and destroying it.
I don't want to sound like an a^*hole but I seriously hate when people say that the end of our (humans little lala world) world will be done by the sun; we wont be here to see it happen. I seriously think that we will do ourselves in with a nuclear bomb. Listen to Einstein: "I know not with what weapons World War III will be fought with, but I do know what weapons World War IV will be fought with; sticks and stones."