Possible? Liquid Water in a Gas Giant?

[NeptuneRise]

Hi there! I'm new here, and I was looking for some information in the Q&A section of this forum but nothing has helped me so far.

I'm working on a Worldbuilding project, where I'm creating a fictional universe, but I do wish the worlds that I create to to be subject to the laws of physics, like other worlds in our real universe.

So, what I was thinking is, could there be a planet, let's say, a gas giant, but with a solid core made of rock and water? Yes, liquid water?

What conditions does such a thing demand?

And what role does the size of the planet play in the formation of a liquid water, in correlation with the distance from it's star?

If it's possible, this is the second part of the question:

This planet that I'm talking about, is in the 4th orbit around this star, making it the last one in a row. How distant should this planet be in order for this liquid water to be maintained, and not freeze over?

Can the necessary heat (which already comes from the star), be achieved with the heat "aid" of 3 hot molten lava moons revolving in close proximity to the gas giant?

Any answers that remotely satisfy the information I need for these questions would be very appreciated. Thank you.

PS: If I get my answers, I may post some other questions regarding the planet.

[Frog march]

I don't think molten lava moons would help much...for a start the planet wouldn't get much energy from them at that distance, and secondly, they wouldn't stay molten for long, on the surface anyway as the heat would radiate a way pretty quickly...

[NeptuneRise]

I don't think molten lava moons would help much...for a start the planet wouldn't get much energy from them at that distance, and secondly, they wouldn't stay molten for long, on the surface anyway as the heat would radiate a way pretty quickly...

Thanks for the answer. So I can erase the moons out of the planetary concept, ok. But, still, is it possible for a gas giant to have such a solid surface, with liquid water? And what conditions must I forge for this to happen, hypothetically speaking?

[NeptuneRise]

So any specific answers? Is it possible? In any way?

[PraedSt]

So, what I was thinking is, could there be a planet, let's say, a gas giant, but with a solid core made of rock and water? Yes, liquid water?

What conditions does such a thing demand?

And what role does the size of the planet play in the formation of a liquid water, in correlation with the distance from it's star?

If it's possible, this is the second part of the question:

This planet that I'm talking about, is in the 4th orbit around this star, making it the last one in a row. How distant should this planet be in order for this liquid water to be maintained, and not freeze over?

Can the necessary heat (which already comes from the star), be achieved with the heat "aid" of 3 hot molten lava moons revolving in close proximity to the gas giant?

These have complicated answers. Sorry if you've read this already, but here's some basic stuff: Gas Giants, Habitable Zones.

[NeptuneRise]

These have complicated answers. Sorry if you've read this already, but here's some basic stuff: Gas Giants, Habitable Zones.

Thank you. Yes I have read them, and the planet in question is 1.8 AU from its star (who is F4 type star), which is not very far, is it? I believe life can develop there, despite that distance. If that's impossible, do let me know.

And, what if a smaller planet composed of rock and ice crashed in a huge gas giant like that? Would that in turn create the desired circumstances/conditions for this planet I have in mind?

Just looking for educated guesses. I have read a lot of things involving Jovians, but I was interested in, what exactly could create such a world, and I haven't found anything similar on the web, and considering a lot of people here are heavily into astronomy and astrophysics, so I thought I would ask this question here and perhaps get an answer.

Thanks for the links anyway, better something rather than nothing I guess.

[PraedSt]

Thank you. Yes I have read them, and the planet in question is 1.8 AU from its star (who is F4 type star), which is not very far, is it? I believe life can develop there, despite that distance. If that's impossible, do let me know.

And, what if a smaller planet composed of rock and ice crashed in a huge gas giant like that? Would that in turn create the desired circumstances/conditions for this planet I have in mind?

Just looking for educated guesses. I have read a lot of things involving Jovians, but I was interested in, what exactly could create such a world, and I haven't found anything similar on the web, and considering a lot of people here are heavily into astronomy and astrophysics, so I thought I would ask this question here and perhaps get an answer.

I think life may be possible, and you could almost certainly find water, but I'm not sure you'd get liquid water in your Jovian.

Does it have to be a gas planet?

[NeptuneRise]

I think life may be possible, and you could almost certainly find water, but I'm not sure you'd get liquid water in your Jovian.

Does it have to be a gas planet?

Well, I'm imagining the planet having really large layers of atmosphere, similar to what we have on Jupiter here, where the solid surface would never be visible, and not anyone would ever guess there is one at all, because in comparison with the gaseous parts of the planet, the solid part would only make a quarter of it.

I need to make large layers of atmosphere planetary part since some of the species occupying the planet live in the atmosphere, and other live on the solid surface. Since I don't know of any other planetary types other than Jovians that fit that category, I thought that a planet as special as that has to be so rare, that a formation of that type can only occur if special conditions are met.

It doesn't have to be a Jovian, but what could possibly replace it?

Again, I know this is not fun for most people here to talk about, since its the 'boring' Worldbuilding stuff (a.k.a fantasy trying to come off as reality), but I really need some help with this lol

I appreciate the comments so far, and thank you for your help, I just need a little more info, and some hypothetical situations that could provide what I have in mind. At least in a basic way.

[Jeff Root]

A deep atmosphere means a very large pressure at the surface. Water on
the surface of a planet with an atmosphere comparable in depth to Jupiter's
would be under such enormous pressure that it would become a form of
ice even if it was at a temperature of hundreds of degrees Celsius. The
graph on this page: http://en.wikipedia.org/wiki/Ice shows temperature
increasing from left to right (in kelvins, K) , and pressure increasing from
bottom to top (in pascals, Pa). Every region above the one labeled "liquid"
is a form of water ice.

You would need to limit the depth of your planet's atmosphere to that which
would give a pressure at the surface of no more than 10,000 times Earth's
normal surface pressure.

-- Jeff, in Minneapolis

[neilzero]

10,000 atmospheres seems more than enough, for the purpose NeptueRise has in mind. You can't see though the atmosphere of Venus at 90 atmospheres. In our solar system, even early 20 th century scientists expected all the gas giant planets, including Venus to have a surface, covered by not much more atmosphere than Earth, until we determined that all 4 have very thick atmospheres.
A civilization advanced enough to construct planets with extremely strong materials, could build a planet larger than Jupiter with vacuum instead of core and mantle. The surface gravity could be about one g and otherwise be very Earth like, except for an atmosphere thick enough that the surface would be invisible from space.
Alternately a manufactured planet could be up to almost Saturn size inflated with hydrogen, or Neptune's size inflated with helium.
Another problem with a planet like Neptune is the surface, if any, is too hot for liquid water. The heat is from the original creation 4.6 billion years ago and radioactive isotopes which have not decayed yet, so a planet created 13 billion years ago should have a cooler surface, perhaps below 200 c = 392 f, which might be tolerable to a life form if the surface pressure is 30 atmospheres. 30 atmospheres with very fine dust and other particulates such as water droplets, should have an invisible surface as viewed from space. Even better, the sun does not need to supply heat, but a little sunlight would be desirable. Neil

[NeptuneRise]

First, thank you for replying Jeff Root and NeilZero, I really appreciate it

A deep atmosphere means a very large pressure at the surface. Water on
the surface of a planet with an atmosphere comparable in depth to Jupiter's
would be under such enormous pressure that it would become a form of
ice even if it was at a temperature of hundreds of degrees Celsius. The
graph on this page: http://en.wikipedia.org/wiki/Ice shows temperature
increasing from left to right (in kelvins, K) , and pressure increasing from
bottom to top (in pascals, Pa). Every region above the one labeled "liquid"
is a form of water ice.

Well, the planet's size would be 3 times that of Jupiter. But the solid part would be close to a third of it.

I can reduce the size if it would cause problems for liquid water, it's no big deal. I just need a large planet with many layers of atmosphere like Jupiter, it doesn't have to be 3 times the size of Jupiter.

The surface, I imagined, could be a combination of Earth-like features with Titan-like features, if that made any sense? It's the best I could describe what I have in mind. If you need any more detail on this particular thing, let me know.

You would need to limit the depth of your planet's atmosphere to that which
would give a pressure at the surface of no more than 10,000 times Earth's
normal surface pressure.

-- Jeff, in Minneapolis

Oh, well ok. How large would the atmosphere part be in comparison with the solid part in the case of 10.000 times Earth's normal surface pressure?

I have no problem adopting this concept for the planet, the more realistic the planet is, the better. So my starting idea is not important, I can reform it to fit realistically.

And I have decided the planet is 2.3 A.U. away from it's star, who is F5V main sequence type star. I believe it would create optimal conditions for life rather then the previous facts I put out.

10,000 atmospheres seems more than enough, for the purpose NeptueRise has in mind. You can't see though the atmosphere of Venus at 90 atmospheres. In our solar system, even early 20 th century scientists expected all the gas giant planets, including Venus to have a surface, covered by not much more atmosphere than Earth, until we determined that all 4 have very thick atmospheres.

Thank you for this information. I will have in mind what you just said. So if the planet is not a gas giant, but an Earth/Titan type of giant planet, it can have a deep atmosphere in similar way to Jupiter?

Do I need to add some information to explain the formation of the planet? Because I might have to give an explanation how it happened.

A civilization advanced enough to construct planets with extremely strong materials, could build a planet larger than Jupiter with vacuum instead of core and mantle. The surface gravity could be about one g and otherwise be very Earth like, except for an atmosphere thick enough that the surface would be invisible from space.
Alternately a manufactured planet could be up to almost Saturn size inflated with hydrogen, or Neptune's size inflated with helium.

LOL, you just described one of my civilizations. They are 'system builders'. They create star systems. But this system, and this planet in particular is supposed to be a naturally created planet, not artificially by a civilization. Though it spawns many species who become space-faring civilizations during it's lifetime as a planetary body, and its a frequent place of events in this fictional universe I'm creating. So I'm aiming this planet to have the potential of creating a thriving world of life forms. If I need to make some more adjustments for this to happen, please let me know.

Another problem with a planet like Neptune is the surface, if any, is too hot for liquid water. The heat is from the original creation 4.6 billion years ago and radioactive isotopes which have not decayed yet, so a planet created 13 billion years ago should have a cooler surface, perhaps below 200 c = 392 f, which might be tolerable to a life form if the surface pressure is 30 atmospheres. 30 atmospheres with very fine dust and other particulates such as water droplets, should have an invisible surface as viewed from space. Even better, the sun does not need to supply heat, but a little sunlight would be desirable. Neil

So I guess that, from 10.000 Earth atmos, I would need to lower it to 30 atmos? I need the surface to be invisible, so if that is enough for the surface not to be seen, then I guess I could take those stats.

200 c? you mean naturally, or if its created? I need a little less heat then that. Any way I could turn that around? If not, I'm ok with taking this into consideration.

Thank you again for the inf .

[EDG]

The clue's in your name. Neptune (and Uranus) are generally regarded to be "icy giants", with a hydrogen/helium atmosphere, a fluid water/ammonia mantle, and a rocky core.
See:
http://en.wikipedia.org/wiki/Neptune#Internal_structure
http://en.wikipedia.org/wiki/Uranus#Internal_structure

[Jens]

Well, I'm imagining the planet having really large layers of atmosphere, similar to what we have on Jupiter here, where the solid surface would never be visible, and not anyone would ever guess there is one at all, because in comparison with the gaseous parts of the planet, the solid part would only make a quarter of it.

The earth already has fairly thick cloud coverage. Couldn't it just be an earth-like planet with slightly more clouds? Then you would never see the surface.

The part about different cloud layers sounds tricky though. Birds don't live in layers basically because their food sources ultimately come from either the land or the sea. I don't think there is a full ecosystem in the atmosphere, so birds and insects don't fly all that high.

[Spoons]

If you had a rocky core three times the size of Earth or Venus, wouldn't such a size make it much smoother a surface, due to the extra gravity?

I was just thinking that this might make depressions for seas / oceans / lakes less likely, which might be a hindrance to life.

I guess with such a huge atmosphere overhead the inhabitants would be very low lying creature too.

[NeptuneRise]

The clue's in your name. Neptune (and Uranus) are generally regarded to be "icy giants", with a hydrogen/helium atmosphere, a fluid water/ammonia mantle, and a rocky core.
See:
http://en.wikipedia.org/wiki/Neptune#Internal_structure
http://en.wikipedia.org/wiki/Uranus#Internal_structure

Well, aren't they gas giants? I believe some of the previous comment people made labeled Neptune and Uranus as gas giants as well.

If by clue you mean making my planet like that type, then I have to say - no way. I need a warm planet, but 200 C* is way too warm lol. Well, I think I know how I can reduce the heat a bit more.

Thanks for the links, I have read about Neptune and Uranus before, and I have already created 5 worlds like them in another star system, but my current focus is the system, and this planet in particular, who is nothing like Neptune or Uranus. Well, maybe their size, but its still not as big as them.

The earth already has fairly thick cloud coverage. Couldn't it just be an earth-like planet with slightly more clouds? Then you would never see the surface.

The part about different cloud layers sounds tricky though. Birds don't live in layers basically because their food sources ultimately come from either the land or the sea. I don't think there is a full ecosystem in the atmosphere, so birds and insects don't fly all that high.

Well, I need thick and deep atmosphere. I don't think Earth has that. I mean, the water and land are visible. One of the key things is that the land is not supposed to be visible. OK, the reason behind it is that the crew visiting the system thinks this is a gas giant, only to discover later that it has a solid surface with teeming life. It's going to be an important event in a story involving this world. So you do get why I need some specific features right? I'm just asking if a thing like that is possible, and if some planetary characteristics don't fit in or make that impossible, I seek to change them.

I need a deep 'world engulfing' atmosphere, but not necessarily different layers of it. I just said that since I read that Jupiter had them or something. Sorry, I'm probably confusing you all, I try my best with my English, if I come off as confusing, let me know, I'll try to explain.

And no, the life forms in the atmosphere are not bird-like creatures. They don't fly, they float. Floating fungi, plants and microbial life. Closest description of them. The 'plants' eat the microbes, the 'fungi' eat the 'plants', and the microbes eat the 'fungi'. So the food sources don't come neither from the land nor the sea. Though some food sources come from the sky, if you look at it from that perspective lol.

I can explain the entire number of eco-systems later if you are interested. I have thought out everything, from the conception of life (from scratch), and all their evolution and development right to the point of becoming space-faring civilizations. That wasn't so hard, the planet stats and characteristics are the tricky part for me, since I'm not that deep in astronomy and astrophysics.

If you had a rocky core three times the size of Earth or Venus, wouldn't such a size make it much smoother a surface, due to the extra gravity?

I was just thinking that this might make depressions for seas / oceans / lakes less likely, which might be a hindrance to life.

I guess with such a huge atmosphere overhead the inhabitants would be very low lying creature too.

The planet revolves slowly on its axis, and it's far enough from the star to have a tolerable force of gravity, that wouldn't have a huge impact on the elements for life there. How would the gravity effect the life there? Higher gravity = Massive/large life forms? 85% of the life forms I envisioned are gigantic anyway, so would that be a problem, or quite the contrary?

I was thinking - if the gravity is not that strong, so the atmosphere does not cause pressure on the life on its surface, but strong enough to hold the atmosphere binded to the planet - Will that solve the problem with having low lying creatures?

If that does not work, let me know how I can fix that.

Again, thank you all for your comments, I really appreciate it

[Spoons]

I wouldn't imagine them to be extremely big, as I'd think efficiency would be key, in avoiding giving too much mass for gravity to work on. I've always imagined, and I'm sure I've seen eburacum45 say something similar, the idea of very low-lying creatures, maybe scavenger type animals or something, with fairly solid legs and skeletal structure, but other than that as trimmed as possible.

Actually, there was a really good episode of a doco I saw, maybe a The Universe episode, on astrobiology, where this sort of thing was hypothesized.

[NeptuneRise]

I wouldn't imagine them to be extremely big, as I'd think efficiency would be key, in avoiding giving too much mass for gravity to work on. I've always imagined, and I'm sure I've seen eburacum45 say something similar, the idea of very low-lying creatures, maybe scavenger type animals or something, with fairly solid legs and skeletal structure, but other than that as trimmed as possible.

Actually, there was a really good episode of a doco I saw, maybe a The Universe episode, on astrobiology, where this sort of thing was hypothesized.

Well, I was thinking the surface dwellers to have the largest creatures on the planet, rather then the flying ones. And I'm still confused - Does extreme gravity produce extreme sized creatures? Or does it do the opposite? Maybe those low lying critters mentioned before?

I have some snail-like creatures (they are part of the 'fungi' type), who are with a very thin body, looks almost like it's smashed to the ground.

I will look into that documentary and get back here with what I have decided to do.

[PraedSt]

And no, the life forms in the atmosphere are not bird-like creatures. They don't fly, they float. Floating fungi and plants and microbial life. Closest description of them. The 'plants' eat the microbes, the 'fungi' eat the 'plants', and the microbes eat the 'fungi'. So the food sources don't come neither from the land nor the sea. Though some food sources come from the sky lol.

Have you read Look to Windward by Iain Banks? He has a world in it that's just a huge a bubble of air, containing big, sentient blimps with cool names like "dirigible behemothaur".

[Jeff Root]

I'm just going to sketch this out in extremely general terms for now.
Maybe you have already thought through all of this.

Gas giant planets are gas giants because they were able to capture and
hold on to large amounts of gas as the Solar System formed. They were
able to do that because of their strong gravity. They had strong gravity
because of their large masses. They acquired large masses at least in
part because they were far enough from the newly-formed Sun that the
strong solar wind did not blow away the gases and small dust particles
that went into them. So the explanation is somewhat circular.

The farther a planet from its star, the more gas it is likely to hold on to.
The more massive a planet, the more gas it is likely to hold on to.
The more massive a planet, the more compressed its core will be.
Mercury is very dense because it has a large iron core. That core is
larger in proportion to the diameter of the planet than any other planet's
core. But Earth is even more dense than Mercury, because it is more
massive, and the weight of all the rock pressing down on the iron core
compresses the core to rather extreme density. As a result, the gravity
at the surface of Earth is much greater than the gravity at the surface
of Mercury.

Denser things tend to sink in a gravity field. Lighter rock floats on denser
rock, and denser rock floats on even denser iron. Likewise, water floats
on rock, and air floats on water.

Earth's atmosphere is composed of a mixture of gases. The different gases
have different densities. But, for the most part, those gases are all mixed
together, not separated into layers by density. That is because they are
gases, and their kinetic energy keeps them mixed. For example, carbon
dioxide is more dense than nitrogen or oxygen. Cold carbon dioxide vapor
coming from a block of carbon dioxide ice sinks to the ground. But it quickly
warms up and mixes with the nitrogen and oxygen, and soon becomes a
completely homogenous mixture. The bottom 100 km of Earth's atmosphere
comprises the troposphere, stratosphere, and mesosphere. Together this
region is called the 'homosphere' because of the uniformity of its molecular
composition. The top of the homosphere is where the atmosphere becomes
thin enough that molecules have to travel relatively large distances before
they collide. The air starts to become less like a fluid, and more like individual
particles on balistic trajectories. Above that altitude, the air starts to separate
into layers by density, via diffusion. The major layers of the heterosphere are,
by decreasing weight: atomic oxygen, helium, and atomic hydrogen. These
gases are not thoroughly separated from each other in the different layers--
they are just markedly more concentrated. There are no sharp boundaries
between these layers.

The atmospheric pressure at the surface of a planet is determined by the
planet's surface gravity and by the composition, temperature, and depth of
the atmosphere. For a given quantity of atmospheric gas, the surface
pressure is greater on a planet with stronger surface gravity. For a given
surface gravity, the surface pressure is greater on a planet with a lower
atmospheric temperature. And so forth.

-- Jeff, in Minneapolis

[Jeff Root]

Since we only know about life on one planet, we have no information
relating variations in gravity to size of creatures.

An eagle is enormous compared to a midge, but they both have what
is needed to fly, find food, reproduce, and so on.

-- Jeff, in Minneapolis

[NeptuneRise]

Have you read Look to Windward by Iain Banks? He has a world in it that's just a huge a bubble of air, containing big, sentient blimps with cool names like "dirigible behemothaur".

No, but I'm going to download it and see what's it about . Thanks!

I'm just going to sketch this out in extremely general terms for now.
Maybe you have already thought through all of this.

-- Jeff, in Minneapolis

Since we only know about life on one planet, we have no information
relating variations in gravity to size of creatures.

An eagle is enormous compared to a midge, but they both have what
is needed to fly, find food, reproduce, and so on.

-- Jeff, in Minneapolis

Thanks for the information Jeff.

Maybe if I change the planet type it could be more realistic in a sense of harboring life? Rather then a gas giant?

Ok, so this is what I came up with:

F5V main sequence type of star

Star Luminosity at Planet - 1.743470998203361 (Earth = 1)

Star's Apparent Size 0.5811243331304294 (Sun viewed from Earth = 1)

The planet is in 4th and last orbit around it.

Distance: 2.5 A.U

Planet Orbital Radius - 2.5763134657051983 A.U

Gravity: 4.5G (Earth gravity = 1G)

Metals and most abundant elements inside its crust: Lithium, Magnesium, Aluminium, Vanadium, Beryllium & Copper

Atmosphere composition of most abundant gases: Hydrogen, Nitrogen, Ammonia, Helium & Oxygen

It would be a terrestrial planet but with huge amounts of hollow pockets inside its make up. 2.5 to 3 times the size of Jupiter, together with the atmosphere.

Would it be realistic enough? Or do I have to make more modifications?

[EDG]

http://www.universetoday.com/2006/10...tune/#more-736 might be of interest

[eburacum45]

One of the key things is that the land is not supposed to be visible. OK, the reason behind it is that the crew visiting the system thinks this is a gas giant,only to discover later that it has a solid surface with teeming life. It's going to be an important event in a story involving this world. So you do get why I need some specific features right? I'm just asking if a thing like that is possible, and if some planetary characteristics don't fit in or make that impossible, I seek to change them.

This is the difficult part. If your explorers wanted to determine the internal structure of your 'rocky planet that looks like a gas giant', they would determine its density by one or several methods, and that would tell them whether the planet had a substantial rocky core or not.

In fact some gas giants, such as Uranus and Neptune, probably have a small rocky core surrounded by a mantle, or shell, of hot high-pressure water ice. But such a mantle would not have any land-surface at all, so if you want a rocky world with continents and so on you would need a much drier planet.

The only way I can imagine a rocky planet could be mistaken for a gas giant is if it is initially suspected of containing a large water-ice mantle, and then later they discover that the planet is extraordinarily dry. This would allow the rocky core to be larger in mass, and there might be just enough water on the surface to form seas and oceans without completely coverng the surface. The atmosphere would be very water-poor on such a planet, and certainly not very Earth-like. I can't imagine how a planet with a thick atmosphere like this could form with such a dry atmosphere, but perhaps it is possible.

[neilzero]

I suggest reducing the surface gravity to about 2.3 g instead of 4.5 g, otherwise large animals will break their bones when they fall down. They hit the ground 4.5 times faster = 4.5 times harder than the same fall on Earth. Yes short legs reduce the typical falling distance. Giraffes likely break a bone far more often than pigs.
Far from the Sun does allow bigger planets at the time planets are formed, but we believe planets often move closer or farther from the sun after they are formed. Otherwise the surface gravity is independent of the distance from the sun = mass, size and average density determine the surface gravity, except a thick atmosphere reduces the effective surface gravity a little = buoyancy.
Many large voids below the surface is not believable at 4.5 g surface gravity, nor at 2.3 g surface gravity, so larger than Neptune is not believable except for a manufactured planet, made from very advanced materials.
As Eburacum suggested (and he is rarely wrong) advanced scientific equipment, such as radar can penetrate hundreds of miles of atmosphere to image the surface. So the secret will only be kept if the space probe is poorly equipped.
A thousand miles of atmosphere is not believable with liquid water on the surface at any temperature, especially if the surface gravity is 4.5 g. Dense water would behave different than ordinary water, much as diamond is different than soot, or graphite, even though all three are carbon.
I suggest dropping vanadium from the list of elements, abundant in the crust and adding calcium, iron, silicone and oxygen. Possibly boron, carbon sodium, potassium, florine and chlorine. Oxygen is approximately 1/2 of the Earth's crust. If it was much less, the atmosphere would quickly lose its oxygen as it combined with the elements in the crust. Free hydrogen is about one part in 5 million in Earth's atmosphere. If there was much more free hydrogen it would quickly combine with the free oxygen. Neil