A question about warmer temperatures...

[Hamstersbane]

What would live on earth be like if the earth got nudged closer to the sun (still livable, but obviously much warmer)? I'm thinking a lot of water dried up, but it's go to go somewhere. Wouldn't increased water vapor mean even higher temps? And at least theoretically, if something happened that moved the earth like that, could you expect a measure of tectonic instability?

[tchernabyelo]

Venus is an example of a planet with plenty of water, but all in vapour form. The temperature at the surface is a few hundred degrees, and that's not merely down to the fact that it's closer to the sun; the same way Mars is much colder than Earth, again because the atmosphere does not retain any significant heat.

As for tectonic instability - it depends what's doing the "nudging". A single impact big enough to shift the Earth's orbit would probably be enough to shatter the crust.

[Hamstersbane]

I'm thinking more a rogue planet or brown dwarf moving through the solar system and pulling the earth a little rather than something hitting it. I know that wouldn't work.

[tchernabyelo]

I'd imagine that anything that's got enough of a gravitational pull to perturb Earth's orbit is likely to set up some pretty unpleasant tidal effects within the molten core, so I think significant tectonic instability could certainly ensue. But I don't know for sure.

[MedievalDude]

And if you're wanting the Earth to pull closer to the Sun, wouldn't you need more mass within the Sun? I'm not sure that something moving through the solar system would pull the Earth in the right "direction" (that is, closer to the Sun). Perhaps it would be better to find an astronomers forum on the internet where you might pose such a question and get a much more detailed answer (or find out what, if anything, could logically alter the Earth's orbit in the way you're imagining).

[Rob Santa]

Late to the party...

Couple of things here. First, Venus does not have any water on it. All the liquid is acid. The water burned off ages and ages ago.

The idea of a rogue planet/star sweeping through the system could work; in fact, it's just about the only thing that could (short of divine intervention). All you need to do to move the Earth closer to the Sun is to slow the Earth's orbit. That could happen with a mass passing behind (and pulling on the Earth as it went) or in front (and causing a whip effect).

Any movement closer would have dramatic effects. While I'm not certain about tectonic action, my gut says nothing major would change unless the temperatures changed enough to destroy all lilfe and liquids on the planet. After all, the core temperature of the Earth is tremendous (5000 degrees at the high end, down to cooler temperatures near the center). How would a few (dozen/hundred?) external degrees affect that situation, and even if it were hotter why would it affect tectonic action?

Faster speed = higher orbit. Slower speed = lower orbit. If the Earth moves slower it moves into a lower (closer) orbit to the Sun.

Now the important question? Why are you moving the Earth?

[Hamstersbane]

Because it's blocking my view of Venus.

Actually, it's some background thoughts for a post apocalyptic novel I'm playing around with.