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Asked by anon-187757 to Stewart, Miriam, Marton, Laura, Kathryn, David on 8 Nov 2018.
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David Ho answered on 8 Nov 2018: last edited 11 Nov 2018 9:45 am
This is one of the questions that nobody knows the exact answer to, we can only guess. Most scientists think that the world as a planet will end when the sun explodes. But don’t worry, that’s around 8 billion years away!
It’s very likely that humans won’t be around on earth for that long. There could be a big extinction events like the one that killed the dinosaurs, or the earth’s environment could naturally change so that humans can’t survive anymore. But again, these are predicted to be many millions of years in the future. Of course, it’s possible that by then we’ll have moved to another planet, or developed new ways of surviving — humans are good at that.
The saddest possibility is that humans will cause the end of our species by something like man-made climate change or a nuclear war. Hopefully this won’t happen, but some people believe it’s a significant risk, and that kind of thing could happen much sooner than these other events I’ve talked about. The world would probably still be around, but it wouldn’t have us on it anymore.
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Stewart Martin-Haugh answered on 8 Nov 2018:
The Earth will be uninhabitable when the Sun expands into a red dwarf, a larger type of star. This will happen around 5 billion years from now.
If we’re still around at that point, we would hopefully be advanced enough to drag the Earth to safety. Otherwise we would have to move to a spaceship and find a new planet. Or maybe we could move to a moon in the outer solar system? Something for the great, great, great…….great-grandchildren to worry about.
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Miriam Hogg answered on 8 Nov 2018:
David and Stewart gave very good answers for this. When the Sun runs out of fuel it will expand into a giant star before shrinking into a tiny white dwarf. In its giant stage it will be as big as the Earths orbit around the Sun!!
A few things might happen here. Either the Earth will be destroyed if the giant Sun engulfs us, Or we are far enough out that the Earth will survive. If the Earth survives the planet will probably become very hot in the giant phase and this will boil away all the water, when the Sun shrinks again the Earth will probably freeze any remaining liquid and gas into ices and turn Earth into a snowball. Life on Earth won’t likely survive all that. But it’s far enough in the future (billions of years) that we might have other things in place to keep us safe!
Comments
anon-187186 commented on :
My science teacher said it would end when all energy is eaquely dispersed, and spread evenly around the planet. Is that true?
David commented on :
Tangerine Cytruss — I think what your teacher might be referring to is something called the “heat death of the universe”. This is exactly what you described, except not just on the planet, on the whole universe — if the universe exists for a long enough period of time all the energy will be so spread out that there couldn’t be any life, or even any planets or stars. The reason this happens is something called the “second law of thermodynamics”, which basically says that as time goes on, things get more and more disordered (like how my bedroom gets messier if I don’t tidy it up). You can read a bit more about it here: https://www.spaceanswers.com/deep-space/what-is-heat-death/