Our Planet is in the Right place It needs to be .

[BAYLOR]

Planet Earth orbits 93 million Miles from the Sun , has a stable atmosphere, gravity plenty of water and thanks to our moon a stable axis. It is the right distance from the sun. Now suppose Venus or Mars had been in earths Orbit instead of earth ? What do you think would have been be the end result?Life as we know it ? Both have different masses sizes gravity ad composition from Earth Life as we know it ?

 

[Mirannan]

Venus is easy; it's nearly the same mass as Earth and has a different composition mostly because its water has been baked out of it. However, that still leaves the matter of axial stability and day length; the Moon, or at any rate the impact that formed it, is probably responsible for both.

Mars is a bit trickier. I think it would be marginally habitable for real-world Earth organisms if put into Earth's orbit, because it's smaller and for that reason vulcanism and plate tectonics have stopped.

 

[BAYLOR]

Venus without a moon or a stable axis , also No tech-tonics so, every periodically the planet turns itself inside out . Both factors would make it hard for any life to evolve at all. If iVenus had Earth moon, that would make a huge difference.


Mars would still be the much the same only warmer. The problem is that without an active core and the magnetic field , there's no way Mars keeps either it air or water. But what about the axial issue ? Hm.

 

[Mirannan]

Well, arguably Venus has no tectonic plates because of the lack of water and the slow rotation. It so happens that water in the upper mantle greatly reduces its viscosity, thus making subduction more likely.

 

[BAYLOR]

Well, arguably Venus has no tectonic plates because of the lack of water and the slow rotation. It so happens that water in the upper mantle greatly reduces its viscosity, thus making subduction more likely.

But having a satellite pulling on the crust is a factor in plate movement as well.

 

[mosaix]

In fact, Earth is only just on in the inner-edge of the Goldilocks zone. A little closer to the Sun and things could have been very different.

 

[Ray McCarthy]

Actually if suitably different size and atmosphere, Mars location (needs a bigger planet than Earth with more greenhouse gasses) or Venus (needs to be more reflective and very little greenhouse effects, possibly a little smaller) could support life. Maybe the Venus planet a little further away from sun. Or a slightly less massive sun.

 

[BAYLOR]

Actually if suitably different size and atmosphere, Mars location (needs a bigger planet than Earth with more greenhouse gasses) or Venus (needs to be more reflective and very little greenhouse effects, possibly a little smaller) could support life. Maybe the Venus planet a little further away from sun. Or a slightly less massive sun.

Venus would also require a moon 1/6 it's size to help give it axis stability and plate tectonics.

 

[Michael Colton]

"A little to the left. No, no, back to the right. Sorry, left and towards me. Actually, let's try swapping Jupiter and Mars. Ah! Bad idea, bad idea. Back where it was."

God arranging the solar system like furniture.

 

[BAYLOR]

"A little to the left. No, no, back to the right. Sorry, left and towards me. Actually, let's try swapping Jupiter and Mars. Ah! Bad idea, bad idea. Back where it was."

God arranging the solar system like furniture.

Definitely not one of my better topics.

 

[BAYLOR]

In fact, Earth is only just on in the inner-edge of the Goldilocks zone. A little closer to the Sun and things could have been very different.

If Earth Had been 89 million Miles away from the Sun instead of 93 million for example?

 

[Venusian Broon]

If Earth Had been 89 million Miles away from the Sun instead of 93 million for example?

By my very (very!) rough calculations shifting the Earth in to an average ~89 million mile orbit from 93 million would boost average global temperatures by ~8 dec C and that is just the effect caused by being closer to the sun and getting more energy from it - there will likely be a large number of consequences and knock-on effects that could do all sorts of things (I would expect that the equator would be uninhabitable and a lot of ice to melt for example if temperatures were to be increased by that sort of magnitude and if ice melts then more energy get absorbed by the surface etc...)

Whether this increase would be enough to cause a permanent runaway greenhouse effect, I don't know. Maybe not (just!)