Providing that we don't kill ourselves from stupidity, the sun will, in approximatly 5 billion years, begin to run out of hydrogen to fuse into helium. At this point the sun's core collapses from lack of fusion reactions. The suns core stops expanding when it gets hot enough to fuse helium into lithium (i think thats the element name... :\). At this point, the outer layers of the remaining hydrogen and helium start to swell. No, this does NOT increase gravitational pull. it DOES however increase the temperature on earth's surface. Eventually the sun will be running low on helium, but by now it won't matter because the sun will be larger than the orbit of Mars, and earth will be a piece of charcoal inside of its atmosphere. (to anyone wondering, the sun fuses elements all the way to carbon before it can no longer fuse, at which point its core collaspes into a white dwarf and its outer layers float off in whats called a "planetary nebula". This nebula can NOT spawn new stars. Yes, i know waaaaay too much about this
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).
As for the poles on the earth reversing, yes that will happen soon, except theres one thing you left out. The fact that at the exact point of equality between the polarity switch, WE WILL HAVE NO ELECTROMAGNETIC FIELD! That means we're all fried by UV radiation, solar wind, gamma rays, all that nasty stuff.
And thats scheduled to happen in our lifetimes, provided we aren't all old geezers right now. Damn. Unless of course we are lucky and the scientists miscalculated.
Or an asteroid could end all life on earth. Studies have shown that it happens regularly, and we're 300000 years overdue. Crud.
Or if we manage to fly to other planets, our entire galaxy is going to crash into the andromeda galaxies in a few trillions of years, and tidal forces would fling our sun (whichever one we happen to be colonizing) into the void (no, us actually hitting another star has a probability of 1 to a gajillion) where we will live until the sun burns out, at which point we'll freeze, alone, in space.
Or if we manage to survive that, the entire universe will either collapse or keep expanding forever until its a cold dark place in which nothing can survive.
Depressing, isn't it?
Openlancer Lead Developer
Edit: Edited something out of your post....Quite immature Blackhole...
Edited by - parabolix on 12/11/2005 4:51:24 PM