raankh said:
Thought I'd chime in with some stellar evolution stuff;
Our star won't explode. About five billion years from now it will have entered its giant phase, becoming a red giant. It will spend about a billion years or so like that, and then shed its outer layers and form a planetary nebula. The Sun will end as a white dwarf, cooling ever so slowly. By cosmic standards it's a very peaceful existence and end.
Thank you. I was gonna point that out myself... The whole "the sun could go supernova" crap is just that -- crap. It's impossible. For a star to go supernova, it needs at least three times the mass of the sun. A supernova occurs because, in **extremely** simplified terms, the core of a star is like a pressure-cooker. The greater the mass of the star (again, in simple terms, "the bigger it is" -- don't point out that volume and mass are two different things, I'm going for something the physics illiterate might keep up with...) the stronger it's gravity is. That force of gravity pulls every single atom in the star inwards, which causes insane pressure to build up in the center. That's right, the "bigger" the star, the greater the pressure. Now, if the star is "big" enough, what do you think happens eventually? What happens to a pressure-cooker if the pressure gets high enough? KABOOM. But the sun doesn't have the mass for the pressure to get high enough for that to happen. So it won't. /highly dumbed-down physics lesson
In approximately half a billion years the Sun's output will have increased to the level where the Earth's oceans will have evaporated. Life as we know it is difficult to imagine at that point. That's well before the Sun moves into it's next phase, or has even expanded significantly from it's present size. So life on Earth will end long before the Sun swells into a giant. Of course, the oceans won't evaporate overnight, so the period leading up to that means increasing salinity, drier and drier conditions as well as profound changes to atmospheric chemistry. That will likely be a mass extinction bonanza.
Also true. However, on the bright side, by then...
A) We won't be around anyway. Evolution will in all likelyhood have seen to that in just a few million years (assuming we don't take care of it outselves, of course).
B) If A is incorrect, then we can always move outwards in the solar system. As the sun gets hotter, Mars and the moons of the gas giants will gradually warm up, and may actually go through the same processes that turned Earth from a lifeless rock to what it is today. Over hundreds of millions of years, that is.
EDIT:
There are any number of ways the world could, most of them already listed. I rather dislike the idea of the Yellowstone super volcano going off as I live in Montana... I'd be vaporized.
a la Nelson: Ha-ha!
