Water World question

[Blue Ghost]

Simply put, how is it that water worlds, pure water worlds with Ice-7 or Ice-9 at their cores, exist?

That is to say the Earth has an iron core that generates a magnetic field that keeps the sun from blowing away our atmosphere with its radiation. But a water world wouldn't have any such magnetic field.

If that's the case, then how is it that they last or exist at all? How come the stars they orbit simply don't boil away their masses?

It seems like whatever atmosphere was generated would be cooked / blown away by the stars radiation, leaving pure H2O exposed to the solar system's sun, and that said water would be vaporized from intense radiation.

Anyway, that's my thinking. If someone has a link, some other reference, or simply knows and can post an answer here, I would be very appreciative.

Thanks!

 

[coliver988]

I don't believe that a water world is just a glob of water in space - just a planet covered in space and could have any core.

A glob of water in space would be interesting though.

Edit: a water world could just be covered in a few feet of water everywhere. If you've not seen Interstellar, there's a scene where they are on what appears to be a water world, complete with really, really large waves.

 

[Redcap]

A pure water world - that is, a world with no solid or molten core of either rock, metal, would not, afaik, be able to retain enough mass to form the gravity required to remain a stable and viable world (or body, whichever is the more applicable term); the water would boil off, and you'd have nothing there. Catch-22. Ergo, a solid or molten core must exist; I'm with Coliver on this - a water world should describe a world with 100% (or as near as ****it) coverage, but with a ocean floor beneath the waves (at whatever depth you care to stick in there).

 

[Blue Ghost]

One of the NOVA docs I saw ("Life After Kepler 186F" I think), they talk about water worlds with a form of ice at the core created out of the massive pressure create by millions of tons of water crushing itself. They said such a world would be quite normal if you were to float on it in a boat or some kind.

But they don't say how such a world could keep on existing, but state that they've found such worlds.

That, verse "water worlds" which are essentially earth sized or mega-earths which are entire covered with water, but are otherwise rocky worlds that have solid cores.

Loose tangent here; another documentary I saw some weeks back stated that there's more water (something like 1.5 to 3 times as much) locked up in the earth's crust than in all of the oceans, and that releasing that water would create a world wide ocean some several feet above mount Everest.

 

[aramis]

One of the NOVA docs I saw ("Life After Kepler 186F" I think), they talk about water worlds with a form of ice at the core created out of the massive pressure create by millions of tons of water crushing itself. They said such a world would be quite normal if you were to float on it in a boat or some kind.

But they don't say how such a world could keep on existing, but state that they've found such worlds.

That, verse "water worlds" which are essentially earth sized or mega-earths which are entire covered with water, but are otherwise rocky worlds that have solid cores.

Loose tangent here; another documentary I saw some weeks back stated that there's more water (something like 1.5 to 3 times as much) locked up in the earth's crust than in all of the oceans, and that releasing that water would create a world wide ocean some several feet above mount Everest.

All worlds will eventually lose any gas and liquid to the void. The thing is, it's not very fast. Earth loses tons of atmosphere daily. About 137 tons per day. about 95 kg a minute. about 1.5kg a second.

About 1 cubic meter at STP.

Now, that's a tiny fraction of the 5.9e21 tons of atmosphere. (or very roughly 9.4e24 cubic meters of atmosphere). Which will take (at current rates) 1.8e18 years to go away... but we'll be fried well before that.

So, if the total mass of said water world is sufficient to form, its sufficient to hold the atmosphere for a billion plus years. Those pure water worlds WILL evaporate. Over a span of billions of years.

 

[tjoneslo]

There are several variables you not explicitly considering.

1) What size is your blob of water? Up to the size of Mars or so (size 5 or smaller) the world does not have the gravity to hold onto the atmosphere (water or whatever). Once your world is larger, the evaporated water forms an atmosphere which the sunlight can't drive off the planet.

2) Where is the planet in relation to the primary? Outside the snow line and the whole blob is probably ice from core to surface. Even well inside the habitable zone, once the blob ices over (the earth did this at least once) there will be no geological activity to undo it. The earth finally unfroze because the volcanoes pushed enough CO2 into the atmosphere to warm it despite the albedo of the ice.

3) What is in your blob of water besides water? The earth's magnetic field is generated by the motion of the molten iron core, kept liquid by the radioactive decay of potassium. I find it very difficult to believe you have a ball of pure water. Comets of all kinds contain dust of various kinds. Rocks contain silicates and various other minerals. Depending on how contaminated the Ice-9 core is with radioactive (supplying heat) and other elements, you may end up with a more or less stable magnetic field.

 

[Blue Ghost]

That's interesting. They, the documentaries, didn't at all address trace elements that might be in the water or ice. It was sort of like "there are worlds purely made of water ... cool huh?", and that was it.

I think it's a very interesting topic, and something worth mulling over when running a "Nomads of the Ocean World" scenario for your players.

 

[G. Kashkanun Anderson]

Well, look, if you can get hydrogen and helium to collapse into a gravitationally rounded object, you can get anything in the universe to do it. And we know that can be done, because the evidence is staring us in the face from sunrise to sunset every day.

Obviously, very few waterworlds are going to be pure water. The only possibility I can see of that happening would be one orbiting a very, very old star, like an extreme or ultracool subdwarf -- something formed, in other words, back when the universe consisted of little else but hydrogen, helium and a smattering of constructed elements like oxygen and carbon. Even so, you wouldn't need these impurities in order to form a waterworld or keep it stable; it should be able to do that by itself easily enough, provided it spends enough time getting its act together out beyond the ice line before wandering into the inner system. The exotic ice states that will make up the mantle and core of such worlds should be well solid enough to stand in for silicates and iron, even under conditions of extreme stellar radiation.

This paper here posits four potential stable states for waterworlds: Iceball, Temperate and Oceanic (aka 'Kevin Costner-friendly'), Sticky Greenhouse (New Orleans times a bajillion) and Pressure Cooker. Only one of these is habitable by human standards -- assuming, of course, you agree that Kevin Costner is a human -- but they are all theoretically viable systems.

This world discovered by Hubble about six years back is regarded as a strong candidate to be an upper-limit version of a Sticky Greenhouse waterworld. This is despite the fact that its orbit -- even accounting for the host star being an M4.5V red dwarf -- bathes the world in exponentially more stellar radiation than even our Mercury gets.

 

[GypsyComet]

On the Science Fiction side, there is Bob Shaw's Medusa's Children, which features an "almost big enough" water world.

 

[tjoneslo]

Using the reference from wikipedia, and an online calculator, a water planet between 1,000 miles and 10,000 miles in diameter, the water pressure is:

500 miles: 80885 bar or about 100Kbar
5000 miles: 808850 bar or about 1Mbar

So depending upon the internal temperature from radioactive decay products, your water world maybe water all the way through, no Ice-IX or anything else. Of course at 1Mbar of pressure, it may as well be a solid.

 

[aramis]

I've seen citations from Sandia National Labs that water pretty much is always solid at 80 kbar.

 

[salochin999]

I played around with a fractal world generator once where the longer time you added for "erosion" the flatter the land got.

Could that process eventually lead to a water world?

(in game terms)

 

[Redcap]

Over the course of a few million years, possibly; It depends on how high the land was above sea level to begin with, what the land was made from, and what kind of water courses were involved (it's all about the geography!). If it was all low-lying sandstone, then it's be relatively quick, but granite and other hard rocks, not so much.

 

[salochin999]

Over the course of a few million years, possibly; It depends on how high the land was above sea level to begin with, what the land was made from, and what kind of water courses were involved (it's all about the geography!). If it was all low-lying sandstone, then it's be relatively quick, but granite and other hard rocks, not so much.

Yeah, reading the history of earth it's 4.5 billion years or something and that is apparently 1/3 the total age of the universe so presumably there might be earth-like planets out there which started sooner and reached the point earth is now a long time ago.

So I was imagining mountains and cliffs gradually crumbling and river mouth silt building up so you might eventually get very flat continents covered in shallow water.

 

[GypsyComet]

So I was imagining mountains and cliffs gradually crumbling and river mouth silt building up so you might eventually get very flat continents covered in shallow water.

If nothing else is happening this can be the result, and is certainly justifiable in the multitude of worlds you may have to detail. Worlds with liquid water in oceanic quantities will often have tectonic activity ongoing, though, so new mountain formation will be happening alongside the erosion.

 

[whartung]

That suggests that the planet has tectonically settled and is no longer pushing land up. I believe we are still pushing more land up than is being eroded, but I'm not really sure. The Pacific Rim is quite active and constantly moving.

 

[Blue Ghost]

That suggests that the planet has tectonically settled and is no longer pushing land up. I believe we are still pushing more land up than is being eroded, but I'm not really sure. The Pacific Rim is quite active and constantly moving.

Indeed it is.

As I stated in an earlier post geophysicists state that of all the world's water, 2/3 of it is trapped or being sucked down below the lithosphere through vulcanism and tectonic activity. There's so much water stored up within and underneath the lithosphere that were it released, the entire Earth would be covered in an ocean that would peak out several inches above mount Everest. Interesting factoid.

Postulation; since hydrogen is a metal (technically speaking), if dihydrogen-oxide is in compressed into solid form, then it is possible that the "sea of electrons" theory holds for ice, and that a "glob of water" type water world, if it was spinning, could generate a magnetic field and act very much like an Earth like body. Said field would protect both atmosphere and water from solar radiation and cosmic rays, again like an Earth world.

Anyway, that's just me trying to warp my brain around the "huge glob of water" hanging in space and being a defacto water world thing.

Comments welcome.

 

[salochin999]

If nothing else is happening this can be the result, and is certainly justifiable in the multitude of worlds you may have to detail. Worlds with liquid water in oceanic quantities will often have tectonic activity ongoing, though, so new mountain formation will be happening alongside the erosion.

good point

my thinking was the history of earth

https://en.wikipedia.org/wiki/History_of_Earth

and how a lot of the world stats could represent an earth like planet just not at the stage the earth is now - at the stage it was a billion years ago or two billion - and then rolling that idea forward what about a billion in the future.