Could an all water planet theorhetically exist?

In summary: Oh sorry, I went off into the weeds.Larrybud, you are correct, the heat of fusion is high enough to keep a water planet molten without any radioactive heating. We think. The phase diagram of water is actually not as well defined as that of other materials, but it is the same principal. In summary, it is highly unlikely for a planet to exist that is completely composed of liquid water. While a planet with an all water surface is possible, it would be strange to find such a pure and long-lasting source of water without any solid material forming a core. However, nothing physically forbids it from happening and there have been mathematical solutions exploring the possibility. The pressure and temperature at the core would determine the state of the
  • #1
larrybud
29
0
Title says it all. Could a planet exist which is completely liquid water?

How about an ice core and water surface?
 
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  • #2
An all water planet would be highly unlikely. An accretion disc composed of mostly water would be very unusual. Accretion discs are believed to be chemically similar to the parent star. A planet with an all water surface would be quite possible.
 
  • #3
It would also be very strange indeed to find so much water that is so pure and stays that way for so long that no solid material accumulates to form a core.

No significant solid impurities or precipitates?

If you made a planet out of nothing but ice comets, it would still be so dirty that the particulates would form a core.
How would you protect this planet from the influx of meteorites?
 
  • #4
How about in regards to physics? Anything in the laws of nature that would prevent it from happening? (keeping in mind that odds of it being low because of dirty comets, etc)
 
  • #5
larrybud said:
How about in regards to physics? Anything in the laws of nature that would prevent it from happening? (keeping in mind that odds of it being low because of dirty comets, etc)
No. Nothing physically forbids it.

If you use the term water loosely. With any size planet, the core will be crystalline ice. I think... Let me check the http://upload.wikimedia.org/wikipedia/commons/0/08/Phase_diagram_of_water.svg" [Broken] again...

Hmm. Maybe not. If it were warm enough.
 
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  • #6
larrybud said:
Title says it all. Could a planet exist which is completely liquid water?

How about an ice core and water surface?

What would the atmosphere be?
 
  • #7
It is rare to impossible probability that only two elements hydrogen and oxygen only be constituents of a planet
 
  • #8
sanjvern said:
It is rare to impossible probability that only two elements hydrogen and oxygen only be constituents of a planet

Let's assume it is as dirty as any Earth ocean. that eases that constraint from "zero" to "small".
 
  • #9
larrybud said:
Title says it all. Could a planet exist which is completely liquid water?

How about an ice core and water surface?

Do you mean a planet with ONLY water as its composition? Or do you mean something like a planet with large seas that effectively cover the entire landmass, resulting in a "ocean planet"?
 
  • #10
William Rowan Hamilton postulated a planet covered with extremely deep oceans and solved the differential equations for the standing waves which would form on this world. His mathematical solution is the basis of the Hamiltonian operator of quantum mechanics, describing the probability of an electron being in a particular place around a nucleus.
So, you aren't the first to wonder about this...
 
  • #11
I don't think it is possible Larrybud, the pressure on the water in the centre of the planet would be so large that it would form into some sort of metallic water, and probably produce a lot of heat. I guess it depends on how small an object you want to call a planet, and how far from the sun.
An ice core seems even less likely as the centre would be hotter than the surface.

What about an all gas planet? Is there some gas which is dense enough to congeal into a ball under gravity, but resistant enough to pressure to not change into liquid or sold in the centre?
 
  • #12
TGlad said:
I don't think it is possible Larrybud, the pressure on the water in the centre of the planet would be so large that it would form into some sort of metallic water, and probably produce a lot of heat. I guess it depends on how small an object you want to call a planet, and how far from the sun.
An ice core seems even less likely as the centre would be hotter than the surface.
This is why I was examining the phase diagram for water. It doesn't take all that much heat to keep water liquid at thousands of atmospheres of pressure.

I haven't worked it out for sure yet because it's difficult to figure out how hot the core would be without radioactive decay to keep it warm.
 
  • #13
Wouldn't the water require a hygroscopic nuclei (dust particle) like rain?
 
  • #14
Gannet said:
Wouldn't the water require a hygroscopic nuclei (dust particle) like rain?
What? So the entire planet would exist as a gaseous vapour until some space dust came along and caused the whole cloud to collapse as rain? :rofl:
 
  • #15
To expand on what TGad stated:

If we compare a water planet to something like the earth.
and just for a quick comparison.

At the Earth's core the pressure is about 330 gigapascals ( 3.5 million atmosphere, 3.5 Mbar) and temperature 5500 K.
Water at that pressure and temperature is a sold, but exibits a metallic property of being able to conduct electricity with free electrons.
As TGlad stated the core would be metallic solid water.

Water has several other phase states besides the well known hexagonal solid, liquid, vapour that we encounter daily. For the solid the hexagonal arrangement of the water molcules at normal pressure gives the snowflake design. At different pressures and temperatures there other different solid (ice) arrangements of the molecules.

So besides the metallic core, which will depend on the temperature of the core, as we move up from the center of the planet of water, various forms of ice with differnet arrangemnets of the molecules will be present, until at a lower pressure of around 1 GPa ( 10 atm ) the phase will be liquid water - that is if the temperature is above 300 K or so. ( closer to 273 k)

If the temperature is below 300K then it is solid ice all the way to the surface and you have an 'ice planet". ( although, at a certain region at 200 Mpa and temperature about 250k or above , there will a layer of water between 2 layers of ice, each of a different solid phase due to the different pressures )
 
  • #16
At the Earth's core the pressure is about 330 gigapascals
But the Earth is composed of material considerably denser than water, or compressed water ice. The pressure at the centre would be more akin to 50-70 gigpascals. Would that equate to a solid?
 
  • #17
Wouldn't any significant mass of water have enough pressure at the center to turn to ice? Wouldn't the receipt of sufficient external heat to prevent this also boil off the water at the surface?
 
  • #18
Google this phrase: phase diagram water

Pick a pressure and a temperature. Determine whether it will be solid or liquid.
 
  • #19
seems unlikley,
as the nebular theory of solar/plantary formation points out the aggregation of core material tends to be an inital collection of dust grains to form Planetesimals then to protoplanets then eventually planets..
but with a trillion galaxies out there each with another trillion stars...
theres always going to be a remote possibility...
 
  • #20
Clearly a planet can't be all water, since it would accrete other stuff along the way, as has been said. However, it appears that a planet with ~50% water might be possible. I found this very nice presentation from Sara Seager at MIT, trying to determine the composition of planets from their masses and radii. Note the sketches on slides 26 and 28 of ~50% water planets, and the phase diagram for water under extreme pressures on slide 29.

www.mpa-garching.mpg.de/lectures/Biermann_10/Lecture2.pdf[/URL]
 
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  • #21
DaveC426913 said:
Google this phrase: phase diagram water

Pick a pressure and a temperature. Determine whether it will be solid or liquid.



Phase diagram of water and all that you want to know.
http://www.martin.chaplin.btinternet.co.uk/phase.html

The same phase diagram as on slide 29 from the link by phyzguy.
 
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1. What is an all water planet?

An all water planet, also known as an ocean planet or water world, is a hypothetical planet that is completely covered in water, with no landmasses above the surface.

2. Is it possible for an all water planet to exist?

Theoretically, yes. It is possible for an all water planet to exist, although no such planet has been discovered so far. The conditions for an all water planet to form would require a larger amount of water compared to other elements during the planet's formation.

3. Could there be life on an all water planet?

It is possible for life to exist on an all water planet, as we have discovered life in extreme environments on Earth such as deep sea hydrothermal vents. However, the types of life forms that could exist on an all water planet may be very different from those on Earth.

4. How would an all water planet affect its orbit and rotation?

An all water planet would likely have a slower rotation due to the lack of landmasses to create friction and slow down its spin. Its orbit may also be affected by the distribution of mass, potentially causing irregularities or changes in the planet's orbit over time.

5. Can we detect an all water planet from Earth?

At this time, we do not have the technology to detect an all water planet from Earth. Most of our current methods for detecting exoplanets rely on changes in a star's light as a planet passes in front of it, which would not be possible for an all water planet. However, with advancements in technology, it may be possible in the future.

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