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If Venus were swapped with mars?


WhiteWeasel

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If venus were swapped with mars, what effects would that have on it's climates? Given enough time, even with all the greenhouse gases it would eventually cool down. It would take many thousands of years, but would it's oceans reform? Maybe be habitable to some kind of life? How much it's atmosphere shrink from thermal contraction?

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If venus were swapped with mars, what effects would that have on it's climates? Given enough time, even with all the greenhouse gases it would eventually cool down. It would take many thousands of years, but would it's oceans reform? Maybe be habitable to some kind of life? How much it's atmosphere shrink from thermal contraction?

It'll still be Venus, but a little cooler. But the greenhouse effect is still one heck of a probelm to overcome.

But Mars on the other hand, might experience natural terraforming rather quickly, which will make it easier to gain public will for a manned mission and a research base. Hell, maybe we'll start colonizing it before 2050 - if all goes well. Its atmospherical density is still an issue.

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It'll still be Venus, but a little cooler. But the greenhouse effect is still one heck of a probelm to overcome.

But Mars on the other hand, might experience natural terraforming rather quickly, which will make it easier to gain public will for a manned mission and a research base. Hell, maybe we'll start colonizing it before 2050 - if all goes well. Its atmospherical density is still an issue.

Okay, perhaps a rephasing of the question, What if venus and mars forme in eachothers places?

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Aw, that just takes all the fun out of it. :D I recommend putting Mars into orbit around Venus. This would create more of a binary planet more so than a planet-moon pair. The tectonic action which results would cause fundamental changes on both objects; let alone the temperature increase on Mars. The continental crust on Venus would become active and CO2 would be absorbed by the exposed rock, thus reducing the mass of the air. Mars' shadow would help cool Venus, perhaps allowing the sulfuric acid rain to reach the surface, which would help weather and expose more rock to the air.

Mars' ices would of course melt and its CO2 pressure increase would help it retain the melted water, rather than being blasted away by the solar wind.

Should be easy, right?

OK, back on topic, Venus as a more massive world, in Mars orbit, would probably have turned out more like Earth, notwithstanding that a large object would have likely hit whatever was in Mars orbit (as it did so). However, our moon is thought to be the result of a similar impact with Earth and our axial spin is decent enough notwithstanding. Mars, on the other hand, in a Venusian orbit, would probably be a lot like Mercury is now. This is due to its mass (similar to Mercury's) and its proximity to the sun. It'd be solar blasted, similar to Mercury.

I'm guessing we'd have bases on Venus (in a Mars orbit) by now, assuming a reasonably pressured atmosphere.

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Had Venus formed in the place of Mars, it could either be an temperate planet (Like Earth) or an tropical jungle planet. Since an day in Venus is longer than a Venusian year, the temperature swings would be drastic, with a year-long summer with the sun out 24/7 and a year-long winter in darkness. But it would be habitable.

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I do not think Venus would change that much. Mars lost its atmosphere because it has a weak magnetosphere, which could not stop solar wind from blowing the gases away. Earth's atmosphere is being blown off (although at a nearly unnoticeable rate), and if the magnetic field was turned off, we would suffer the same fate as the martians. Venus is almost as massive as Earth, so the magnetosphere will protect its greenhouse gases from the even weaker solar wind, inverse square law and all. It would get a bit cooler of course, but the greenhouse effect is strong enough to counter it.

Mars, on the other hand, would become scorching hot. Just like the Moon's side facing the Sun, the surface would heat up without an atmosphere's protection in the intense light.

What this change in the solar system would do to Earth's orbit is a different question. It could be disasterous, or it could be nothing at all.

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Venus is almost as massive as Earth, so the magnetosphere will protect its greenhouse gases from the even weaker solar wind, inverse square law and all.

Venus no intrinsic magnetic field, as it doesn't have a similar 'internal dynamo' to earth.

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I think you need to give us a little more parameters to speculate upon.

Okay, perhaps a rephasing of the question, What if venus and mars forme in eachothers places?

Formed? If whatever planet formed out where mars is now would accrete the same material as before and it would still be the same. Only difference in your idea would be a name swap. Need to specify what would be different, or at what point in time to magically swap them.

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From the context of WWs OP and additional post, I'm of the opinion that what he implied is that the object we call Venus (in terms of mass and chemistry) were to be formed in Mars orbit and vice versa. This would imply different accretion results. But there are still a lot of variables that we could change or keep for either object, as the new locations relative to the sun create new consequences.

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If venus were swapped with mars, what effects would that have on it's climates? Given enough time, even with all the greenhouse gases it would eventually cool down. It would take many thousands of years, but would it's oceans reform? Maybe be habitable to some kind of life? How much it's atmosphere shrink from thermal contraction?

Venus can't form oceans unless water is introduced from somewhere else.

Water vapor in a planet's upper atmosphere can be split into hydrogen and oxygen by high-energy radiation. Because the hydrogen is so lightweight, it may be moving fast enough to escape the planet's gravity. This means that over geologic time, planets that can easily retain water vapor will lose water from their atmospheres.

The only reason Earth doesn't lose its water is because it has an atmospheric cold trap: basically, Earth's stratosphere is so cold that the water vapor freezes out and doesn't reach the exosphere.

When Venus's original oceans boiled, the resulting water vapor was lost to space. Its current atmosphere is pretty much bone dry.

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This is about the effects on just the climate of venus, not it's gravitational effects on other planets. So if venus were swapped with mars, it would still be a desert world from what Armchair said. Now if it formed in mars' place, it's composition would be a little different due to forming in a different place, but still have the major characteristics: extremely thick atmosphere, slow rotation, no moon, 10% weaker gravity than earths, geologically active, etc... What would Venus be like?

Since it's further away from the sun, I'm guessing it's atmosphere would less deep from lack of thermal expansion, but i'm not sure if it's pressure would be less, assuming it's the sameish amout of gas, it would just take up less space meaning it would be more dense right? And the more material in the same amount of space, the more pressure.

Edited by WhiteWeasel
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Wouldn't Venus out at Mars's orbit would be even colder at the stratosphere? Thus if a Venusian mass had formed at Mars orbit – while you may be right, Kilmeister, your answer is pretty obviously just playing semantics – wouldn't it then have retained more water in its atmosphere? Mars, meanwhile, relocated to the inner edge of the Goldilocks zone with a much thinner atmosphere than Venus, would still be bone-dry by this logic due to slow hydrogen loss.

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  • 10 months later...

Those that noted Venus' and/or Mars' lack of a magnetosphere are correct. Both of those worlds have a solid (or nearly so) core, preventing any magnetic feild caused by moving metallics (a dynamo) from reaching beyond their surfaces. Because of this both worlds have lost mind-blowingly large masses of atmosphere to solar winds. The reason Venus has such a thick atmosphere, especially when compared to Mars, is that Venus' surface is being boiled adding to the atmoshperic volume. Currently this process is matching the pace of loss. If the two bodies formed with each other's mass, then the large Mars would still be a cold planet with a thin atmosphere and the small Venus would still be an inferno with a thick atmosphere. This would be for the same reasons that their temperature and atmospheric qualities are currently.

To get an habitable Venus or Mars (looking long term achievement and habitability), both planets would need a large moon that would knead their cores starting a dynamo (to create a magnetosphere protecting the atmosphere from solar winds, and the surface from lethal levels of radiation), stabalizing their wobble, and breaking Venus' near tidal lock with Sol.

tl;dr moons have more effect on planets than location

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Moving an entire planet?

Yeah, believe it or not… the thought has occurred. And been seriously worked on, in peer-reviewed literature:

How To Move A Planet, by Paul Birch

(Yes, Paul Birch thought big. Very, very big. Another of his papers considers how to roof-over Jupiter (yes, the entire planet) and develop the "surface" at the 1 G level)

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Mars' ices would of course melt and its CO2 pressure increase would help it retain the melted water, rather than being blasted away by the solar wind.

co2 dint help to prevent h2 escape on venus. With mars gravity this effect would be even faster.

Venus no intrinsic magnetic field, as it doesn't have a similar 'internal dynamo' to earth.

I guess the main venus issue who remove all the water of venus was due high amount of radioactive materials in its core.

These mean that the core never get cold enoght to become solid, so never had a magnetic field to avoid the H2 escape.

Also the low rotation speed of venus is also a mistery.

Edited by AngelLestat
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Yeah, believe it or not… the thought has occurred. And been seriously worked on, in peer-reviewed literature:

How To Move A Planet, by Paul Birch

(Yes, Paul Birch thought big. Very, very big. Another of his papers considers how to roof-over Jupiter (yes, the entire planet) and develop the "surface" at the 1 G level)

That is amazing. Forget swapping Mars and Venus. My new life goal is to to put Mars in orbit of Venus and place the entire Venus-Mars system in the same orbit as Earth just 180degrees around (so the two systems don't perturb each other).

Of course, this assumes that the new Venus hill-sphere allows for a Martian moon.

Look for this on Kickstarter.

As an ISA question, would doing this change both planets to dwarf planets as the center of mass for the system would be outside either planet? Maybe doing this would require a new ISA classification of binary planet.

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That is amazing. Forget swapping Mars and Venus. My new life goal is to to put Mars in orbit of Venus and place the entire Venus-Mars system in the same orbit as Earth just 180degrees around (so the two systems don't perturb each other).

Of course, this assumes that the new Venus hill-sphere allows for a Martian moon.

Look for this on Kickstarter.

As an ISA question, would doing this change both planets to dwarf planets as the center of mass for the system would be outside either planet? Maybe doing this would require a new ISA classification of binary planet.

180 degrees (L3) isnt stable. But 60 degrees is- they'd be in each other's L4/L5 lagrange points.

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That is amazing. Forget swapping Mars and Venus.

If you read the paper, you'll find Birch thought even bigger than that. Near the end he figures out how long it would take to bring the Sun and Alpha Centari to relative rest using this method. Targeting the mass streams is evidently… just an engineering problem. Conclusion: it would only take about 1 kyr to bring the two systems to relative rest.

- - - Updated - - -

Of course, this assumes that the new Venus hill-sphere allows for a Martian moon.

While the Hill sphere is an excellent approximation for satellite stability, I think it might not be valid when the "satellite" is fully 1/3rd the mass of the "primary" :)

- - - Updated - - -

180 degrees (L3) isnt stable. But 60 degrees is- they'd be in each other's L4/L5 lagrange points.

I suspect he was talking about making Mars and Venus a co-orbital planet pair (the two orbiting a common barycenter and the barycenter in a reasonable orbit around the Sun), not putting Mars at Venus's Lagrange point. For the pair in question L4/L5 wouldn't be stable anyway (Mars is much too big; L4/L5 are only stable when the mass ratio is around 26:1 or better, which isn't even close to the case for Venus:Mars).

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I suspect he was talking about making Mars and Venus a co-orbital planet pair (the two orbiting a common barycenter and the barycenter in a reasonable orbit around the Sun), not putting Mars at Venus's Lagrange point. For the pair in question L4/L5 wouldn't be stable anyway (Mars is much too big; L4/L5 are only stable when the mass ratio is around 26:1 or better, which isn't even close to the case for Venus:Mars).

I was thinking about Venus:Mars in a cobaryous partnership, and then the pair be put in the Sun-Earth L3 (so you're both right). Venus:Mars would be massive enough to significantly affect the orbit of Earth. So that Earth would need to be in the Venus:Mars-Sun L4 while Venus:Mars would be in the Earth-Sun L5 (or vice-a-versa). Venus:Mars would have a mass ~57% that of Earth:Moon, which seems to be well within the L4/L5 tolerances.

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