And if so, why isn’t it?
Just remembering all the sic-fi stories imagining Venus as a sister-Earth, only wet and tropical. All put paid by the various Venus probes.
But could Venus have developed differently to be more Earth-like? If so, why didn’t it?
You’d need at least two things: You need to shed the vast majority of that atmosphere, and you need faster rotation. Even then, it’d probably still be too hot, except at the poles.
It’s too close to the sun and has no magnetosphere of its own.
Venus is apparently right on the edge of the goldilocks habitable zone.
So the interesting question is why does it have such a thick atmosphere and no magnetosphere? Without the runaway greenhouse effect its temperature would be much more reasonable.
Venus rotates the opposite way to all the other planets in the solar system, and has a ridiculously long day, do we know why that occurred and if thats the same reason it has no magnetosphere? Apparently it does have a molten core.
I am not up on the current science regarding Venus, do scientist believe it once had oceans that were boiled off?
but why does it have such a thick atmosphere, compared to Earth?
I’ve read that it’s basically because Venus is a bit too close to the sun. Instead of being like the earth, where everything kinda reaches an equilibrium (usually quite a bit hotter than it is now, btw) Venus instead is basically a case of greenhouse gases gone wild. Since things don’t get a chance to cool down and condense and drop back to the surface, everything just gets hotter and hotter, which causes more gases to boil off from the surface and go into the atmosphere, which feeds the greenhouse effect, and continues to make it hotter. So everything just keeps making it hotter with a thicker atmosphere until you end up with the atmospheric hell that it is now.
I’m not sure how accepted it is, but I’ve also heard a theory that another problem with Venus is that its crust is too thick. Earth vents heat because its surface isn’t completely solid. You’ve got these big tectonic plates that shift around and allow heat to escape through their edges. Venus, by comparison, has a solid surface with no tectonic plates. As a result, heat can’t get out. Over time, this causes an increase in volcanic activity, which throws even more greenhouse gases up into the air. Eventually, the surface of the planet heats up so much that it all melts at once, releasing huge amounts of heat. After the heat is released, the surface cools, freezes solid, and the whole thing starts all over again.
The slow rotation is due to tidal friction from the Sun and (to a very small but still significant degree) the Earth. It’s similar to how the Moon has become locked to the Earth. The lack of magnetosphere is due to the slow rotation, since the process which produces the magnetic fields of stars and planets depends on rotation.
When I’ve imagined life on other planets, I thought this would be an interesting dynamic. You could have a planet with life existing on both poles, separated by impassible deserts. Life could evolve at the poles completely independent of each other until finally at some point, the technology is developed for one species to travel beyond the desert and visit what would essentially be an alien world.
I read a paper five or so years ago that said that Venus’s slow rotation was an effect of its very thick atmosphere. With an Earth-density atmosphere, it wouldn’t have the slow rotation it does.
That was Earth, 55 million years ago (and possibly on a couple of other occasions as well). Global temperatures rose to the point where the area around the equator was simply too hot to support life. Exactly what caused this warming seems to be a matter of debate, but there was clearly a large extinction event associated with it.
The entire earth has pretty much frozen solid too (about 650 million years ago).
I remember when Venus was supposed to be a ‘twin planet’ to Earth.
Mysterious and monstrous valleys of green skin women awaited our first explorers.
Then those dang probes went there and screwed up everything.
Until then, there were Venusian women waiting for use Terran dudes.
…
Yeah, it is a very interesting question. The surface temperature of Venus (~460C) indicates that its atmosphere traps a huge amount of solar energy. It is closer to Sol than Earth is (obviously) but that in and of itself, doesn’t explain the remarkable difference between the two. Venus’ atmosphere is almost enitely CO2, and we all know what that means. The landscape is also dominated by extremely active tectonic activity which is (pretty much doubtless) the source of the CO2.
I wonder if it had accreated (sp?) just a bit further out, if it would have developed into something else. Likely, it would have. Look at how profoundly differently the terrestrial planets have ended up. You have a crispy critter planet that is probably only going to be useful as a solar collector, then you have a volcanic wasteland, then you have us (whew), then you have a very cold and arid planet which may or may not have subterranean (is that the right term… subarieasian) life or remnants of previous life.
It appears from one sample of planetary systems, that only a small range of orbital distance from the primary star will allow lfe to develop.
But, we only have one sample.
Not enough to form a valid hypothesis.
So, quite obviously, we must send probes to other stars to study their planetary systems.
<Sits back in in lounger, puffs on his pipe, and turns on a rerun of ‘Bonanza’>
Mars’ problem seems to be mostly due to the fact that its layers aren’t as differentiated: Earth has most of its iron and nickel in the core, with most of everything else layered on top. But Mars has much less of a core, with its iron mixed in with everything else (hence the red at the surface). In turn, the lack of a significant core means that it doesn’t have as much of a magnetic field, and the lack of a magnetic field apparently enabled the solar wind to blow away most of Mars’ original atmosphere.
These are not necessarily contradictory explanations. The tidal slowing is no doubt enhanced by having a thick atmosphere to make a big tidal bulge.
Shoot, terraforming Venus or Mars is going to take more work than I’m willing to commit to.
Maybe some other Milky Way planet instead. But I’m not going to start planning until at least after summer school.
Sorry, but we’re staying here for a while.
Right. As I understand it, the retrograde rotation of Venus is due to an interaction between solar tides in the planet and those in its atmosphere. If it were not for that, Venus would be tidally locked to the Sun. Tides raised by the Sun in the body of Venus would de-spin the planet in ~10[sup]8[/sup] years if no other torques were acting.
Query: where does the energy from the rotation go when the planet gets tidally locked? It has to be conserved somehow, correct?
Heat. The deformation of the planet varies with time, converting the rotational energy to heat.
As a general rule, whenever the question is “where did the energy go?”, the answer is almost always “heat”.
Cite? I find that hard to believe, considering that the ocean was still there.