If a drop of water the size of Earth was orbiting our Sun at the same distance, what would it look like? How much of it would turn into ice in the center, what would gravity do to the ice in the center, would it have strange currents, would it ever rain, etc…
A drop of water would be less dense, so if you wanted it to orbit at the same distance and speed as the earth, it would have to be a lot larger.
A physicist would have to tell you if a body of water with the mass of the Earth would simply boil away into space, or have enough gravity to hold itself together with a frozen surface.
i would have to say it would have an atmosphere of water vapor. i think the intense pressure at the core would keep the water in a liqued state no matter the temprture.
I think the pressure would tend to break the asymmetric water molecules apart, and then the oxygen and hydrogen would liquify.
Well you’d have the same escape velocity as earth and we know that water vapour exists in our atmosphere. The water vapour would likely dissociate to H2 and O2 likely going to O3 and regulating the amount of dissociation that could happen. Even if it did you’ve got about 1x10^24 kg of the damn stuff so it’s not going anywhere fast.
Water vapour is an excellent greenhouse gas so you might wind up with a warm moist greenhouse type of environment. Now would you have clouds? There’s nothing to act a nucleation sites unless some sort of plankton gets airborne, assuming they evolve in time to prevent excessive heating. I’m betting no ice until clouds form.
I would think the pressure would cause the inside of the planet to be at a constant boil, and because most of the planet would be, well, liquid or gas, a huge amoung of convection would be going on.
Without any land to keep the water from circulating freely through the planet It’s unlikely that there would be any significant ice formation.
The pressure would cause heat once (when it is 1st pressurized) constant pressure doesn’t cause constant heating.
Clouds may form from space dust (to act as nucleation sites) and the planet would not have a magnetic sheild so I would wag would get a lot more small stuff from space (manily the star it was orbiting). If so the day side might be totally clowded up.
interesting, i didn’t think of that. it makes since though. wouldn’t the liberated hydrogen and oxygen float to the surface making an atmosphere of hydrogen and oxygen? one that a single crashing meotorite might ignite?
by the way my above post was in response to el smasho’s post.
The pressure would cause heat once (when it is 1st pressurized) constant pressure doesn’t cause constant heating.
Clouds may form from space dust (to act as nucleation sites) and the planet would not have a magnetic sheild so I would wag would get a lot more small stuff from space (manily the star it was orbiting). If so the day side might be totally clowded up.
Not true. When you’ve got as big a mass difference as the Earth and the Sun, the mass of the smaller body has almost no effect on the orbit. If you put Jupiter at the Earth’s position and speed, the orbit would be almost identical to if you put a single raindrop there.
I imagine that near the surface of this hypothetical planet, things would look much like they do on our own (but with much more in the way of large-scale ocean currents). In the center, though, I confess that I’m stumped. Certainly, if you put water under that kind of pressure, it’s going to do something interesting to it, but I’m at a loss as to what that would be. My best guess is that, at some depth, there’d be a phase transition from “regular” water to some more dense form, which would probably be solid. There might in fact be several such phase transitions, and there may even be a chemical transition (perhaps at extreme pressure, something like H[sub]4[/sub]O[sub]2[/sub] would be stable, for instance). But unfortunately, I don’t think that anyone’s ever studied what happens to water at such extreme pressure.
I’m also not sure about the temperature at the center, but this is a little less in the realm of the unknown. As the planet formed, it would be heated in the center. In a mineral planet like the Earth, this original heat still hasn’t had time to dissipate completely. Actually, the Earth is also heated by radioactive decay in the core, but even without that, the core would still be hot. Now, water, on the one hand, has a higher specific heat than earth, which would cause it to tend to hold onto its heat for longer, but on the other hand, with the bulk of the planet being fluid, you’d end up with a lot more convection than you get with the Earth, which would tend to cause the planet to lose its heat. Someone better versed than I in fluid dynamics might be able to calculate which of these effects would be more significant.
The planet would also be subject to dramatic tidal distortion from the star’s gavity.
I tried looking for some links on the subject, but this is all I could find. Which is a post asking about a Jupiter sized planet that is made mostly of water.
“So, the structure of the planet will probably be: a layer of ordinary ice on top, a layer of liquid water underneath, and a core of Ice VII at the bottom. It’s possible that instead of a liquid water layer, there will be layers of Ice II, VI, and/or VIII, if the planet’s core is relatively cool. It’s also possible that another (probably solid) form of water will exist beneath the Ice VII layer.” Re: What would a planet made mostly of water (H2O) be like? or Phase Diagram of Water (ICE: II, VI, VII, and VIII)
I tried looking for some links on the subject, but this is all I could find. Which is a post asking about a Jupiter sized planet that is made mostly of water.
“So, the structure of the planet will probably be: a layer of ordinary ice on top, a layer of liquid water underneath, and a core of Ice VII at the bottom. It’s possible that instead of a liquid water layer, there will be layers of Ice II, VI, and/or VIII, if the planet’s core is relatively cool. It’s also possible that another (probably solid) form of water will exist beneath the Ice VII layer.” Re: What would a planet made mostly of water (H2O) be like? or Phase Diagram of Water (ICE: II, VI, VII, and VIII)
Not really. The earth isn’t completely rigid and deforms due to tidal force. And the surface of the earth’s ocean deforms almost exactly the same amount as a completely liquid planet.
Yes, but the earth is still more rigid than water and the oceans are a very thin layer compared to the entire volume of the planet. Additionally, the rotation of the earth in reference to the sun and moon means that it only experiences tidal forces along a particular axis for a limited amount of time before being flexed in another direction, while internal drag would soon stop the rotation of a water planet.
While the oceans are are very thin layer, they’re still quite thick enough that the bottoms aren’t exposed at low tide. So I don’t see why the tides would be any larger for an all-water planet. And the direction of the tidal bulge (always towards the Sun) would be the same for an all-water planet as for a mostly mineral planet. I further can’t see why the tidal friction would be any greater for an all-water planet: If anything, it seems like it would be less.
That looks like a pretty good explanation, Nim. If we’re looking at the outer solar system (where solar heating is less significant), we can also take several of the moons (such as Europa) as examples (albeit a good bit smaller than Earth). But I was interpreting that the OP was interested in a planet with a liquid surface, not an ice crust.
I think you missed my point. Yes of course the tidal bulge is going to be towards the sun, but in the case of the earth it’s rotation means that it the part of it that gets squeezed is going to get stretched six hours later so the forces dont have a chance to act on the earth in a particlar axis for long. Have you ever tried spinning an egg? a raw one slows down pretty fast because the insides are liquid but a hard boiled one spins for a long time. Try it.
Yeah, it sounded more like what you’d call an ice planet rather than a water planet.