Nyrath Posted October 22, 2009 Report Share Posted October 22, 2009 http://bldgblog.blogspot.com/2005/10/earth-75-billion-ad.html For if your player characters' time machine gets stuck in "race-to-the-future" mode. Quote Link to comment Share on other sites More sharing options...
Steve Long Posted October 23, 2009 Report Share Posted October 23, 2009 Re: Earth: 7.5 Billion AD Cool -- great find! Quote Link to comment Share on other sites More sharing options...
Cancer Posted October 23, 2009 Report Share Posted October 23, 2009 Re: Earth: 7.5 Billion AD The ocean-evaporation thing has already happened to Venus, probably. There are models that suggest that the increased temperature after ocean loss causes global volcanism to break out, because the thin oceanic crust needs the cooling blanket of liquid water to keep from heating up and melting. Once all the water and CO2 are in the atmosphere, the runaway greenhouse heating raises the temperature more to the point that continental crust minerals break into weaker rocks, and the continents also "relax" plastically and go volcanic. Result: the whole planet gets repaved with volcanic deposits. It seems to have happened to Venus about 800 Myr ago. Tidal evolution of the Earth-Moon system isn't mentioned, but that's a longer timescale. I rather doubt the Earth will get locked to the Sun. The tidal braking due to the Sun is weaker than that of the Moon, and the Earth-Moon system trades angular momentum back and forth much faster than the Earth-Sun system. The last evolution computation I've seen for the Sun indicated that Earth would not be consumed by the Sun when it becomes a red giant, but only because of mass loss by the Sun as it ascends the giant branch. The Sun will expand to slightly larger than 1 AU (so it will reach past where Earth is now), but solar mass loss means loss of gravitational binding energy, and the orbits of all the planets will have grown somewhat. So, Earth will escape being engulfed and destroyed. Mercury and Venus will not. Quote Link to comment Share on other sites More sharing options...
ghost-angel Posted October 23, 2009 Report Share Posted October 23, 2009 Re: Earth: 7.5 Billion AD Well, that's a relief. Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted October 23, 2009 Report Share Posted October 23, 2009 Re: Earth: 7.5 Billion AD Hurrah for that. Quote Link to comment Share on other sites More sharing options...
Drhoz Posted October 24, 2009 Report Share Posted October 24, 2009 Re: Earth: 7.5 Billion AD Well' date=' that's a relief.[/quote'] agreed - after all, Earth is where I keep all my stuff Quote Link to comment Share on other sites More sharing options...
Asperion Posted October 25, 2009 Report Share Posted October 25, 2009 Re: Earth: 7.5 Billion AD Tidal evolution of the Earth-Moon system isn't mentioned' date=' but that's a longer timescale.[/quote'] Actually (even though not mentioned) before this happens, the Moon will have lost orbit and flew off to who knows where. I believe that there is one of two possible paths for Luna, either in towards Sol or out towards the Oort Cloud. Either way there will not be any consideration of what will happen there. Quote Link to comment Share on other sites More sharing options...
dmjalund Posted October 25, 2009 Report Share Posted October 25, 2009 Re: Earth: 7.5 Billion AD actually theres a third option for the moon, it could park itself in a Trojan orbit 60 degrees away from the Earth's orbit around the sun Quote Link to comment Share on other sites More sharing options...
tkdguy Posted October 25, 2009 Report Share Posted October 25, 2009 Re: Earth: 7.5 Billion AD Humanity would probably be long extinct by that time. But suppose you have a colony of humans in suspended animation while in space reviving and resettling the planet when they return. Maybe they did it on purpose in response to a global catastrophe (like the Tom Baker era Doctor Who episode "Ark in Space") or they were looking for a new planet (like Planet of the Apes). Definitely the life forms they encounter would be unfamiliar to them, so they may as well be on another planet. Quote Link to comment Share on other sites More sharing options...
Cancer Posted October 25, 2009 Report Share Posted October 25, 2009 Re: Earth: 7.5 Billion AD Right now the Moon's orbit is getting larger with a rate of about 4 cm a year. My understanding is that process will continue for quite some time while the earth spins down, and then the Moon will spiral inward, eventually reaching the Roche limit and being destroyed. I don't know the timescale for the spiral-in process, since I think it's dictated by dissipation of orbital kinetic energy + Earth's rotation energy and angular momentum coupling driving the Moon inward. I'll have to see if I can find that information. Quote Link to comment Share on other sites More sharing options...
Cancer Posted October 25, 2009 Report Share Posted October 25, 2009 Re: Earth: 7.5 Billion AD Humanity would probably be long extinct by that time. But suppose you have a colony of humans in suspended animation while in space reviving and resettling the planet when they return. Maybe they did it on purpose in response to a global catastrophe (like the Tom Baker era Doctor Who episode "Ark in Space") or they were looking for a new planet (like Planet of the Apes). Definitely the life forms they encounter would be unfamiliar to them' date=' so they may as well be on another planet.[/quote'] It pays to remember in this sort of context that multicellular organisms only evolved 700 Myr ago or so. We're talking about time intervals which exceed that needed for most of the kind of biological evolution we self-centered metazoans think is important. Quote Link to comment Share on other sites More sharing options...
SvZurich Posted October 26, 2009 Report Share Posted October 26, 2009 Re: Earth: 7.5 Billion AD I'm still surprised the moon is still in orbit. Thought for sure we'd lose it due to a nuclear accident supposed to happen a decade ago. Was so hoping to explore space with Eagle landers and meet alien civilizations. We haven't been to the moon in my lifetime, and I am 35. Sad. No Space 1999 adventures for me. Quote Link to comment Share on other sites More sharing options...
Lawnmower Boy Posted October 26, 2009 Report Share Posted October 26, 2009 Re: Earth: 7.5 Billion AD Stupid government, not letting us ship all our dangerously unstable radioactive waste in rockets to the Moon, so it'll be safe. Plus, the Moon adds to Earth's livability, so if it rocketted off into space on a nuclear FTL-except-when-its-not explosion, the landlord would have to cut our rent. That's better than getting a room-mate! Quote Link to comment Share on other sites More sharing options...
SvZurich Posted October 26, 2009 Report Share Posted October 26, 2009 Re: Earth: 7.5 Billion AD If the moon were gone, it would be easier to sleep (assuming no meteors hit) at night without that extra light keeping us up. Plus we wouldn't have to worry about corporate logos being added to its surface to annoy us. Although I did like that logo in Hancock... Quote Link to comment Share on other sites More sharing options...
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