Was Earth a Migratory Planet?

astroengine writes "Why our planet isn't a "snowball Earth" — a dilemma called the 'faint young sun paradox' — has foxed solar and planetary scientists for decades. Since the Earth's formation, a planet covered in ice should have stifled any kind of greenhouse effect, preventing our atmosphere from warming up and maintaining water in a liquid state. Now, David Minton of Purdue University has come up with a novel solution that, by his own admission, straddles science fact and fiction. Perhaps Earth evolved closer to the Sun and through some gravitational effect, it was pushed to a higher orbit as the Sun grew hotter. But watch out, if this is true, planetary chaos awaits."

On the upside though

[Fluffeh]

If this is the case, and the "chaos" that awaits is us migrating into a higher orbit, then whoopee, there goes us having to worry about the greenhouse effect... Oh wait... this isn't just another excuse not to curb our burning of fossil fuels is it?

Wouldn't a giant impact change its orbit?

[Brad1138]

Kind of like this [wikipedia.org]...

Re:Fairly stupid response

[Dialecticus]

Even your argument that "everything is a poison in large quantities" is stupid, because it's not the CO2 harming you if you go in the garage and turn on the car - it's the fact you are not getting oxygen. The CO2 itself did not hurt you.

Actually, it's not CO2 nor lack of oxygen that kills in this situation, but rather CO. As I understand it, hemoglobin bonds preferentially to CO over O2. Once a red blood cell has absorbed CO, it doesn't want to let go even when exposed to O2. This means that one can effectively suffocate even when there's plenty of O2 available to breathe.

This is why CO is sometimes used on meat. It keeps the meat bright red and healthy-looking so it will look nice on display in the grocery store. Without it, I think meat would tend more toward purple.

Re:The Inside Scoop

[spacemandave]

During the Archean, the time period relavant to this study, tidal heating was not terribly important. The larger internal heat from radioactive decay was higher, yet still dwarfed by the energy input from the Sun in setting the surface temperature of the Earth.

I am quite skeptical about this

[ctrl-alt-canc]

One of the amazing consequences of the Kolmogorov-Arnold-Moser theorem [math.ethz.ch] (KAM) is that the Earth orbit is stable, despite the influence of Jupiter. Stable in this context means that the orbit perturbations caused by Jupiter and the other planets don't cause the Earth orbit to move too close or too far from the Sun, causing dramatic changes of temperature.
Chaos theory when gravitation is involved is not so chaotic as one could expect: the KAM theorem tells us that multi-body systems governed by gravitation law have intrinsic stability regions.