Liquid Giants

[Henry Krinkle]

I read today that some astronomers refer to the Jovian planets as liquid giants. I much more commonly hear them referred to as the gas & ice giants. So how recent is this change in terminology? is it widely accepted? or even correct?

Thanks for replying in advance.

[Hungry4info]

The Jovian planets are more fluid than liquid. Fluid is a state of matter that can fill its container. That will be either gas or liquid.
But that terminology is not commonly used.

[AriAstronomer]

I suppose the classic term 'gas giant' refers to the fact that all the material in Jupiter were it on earth at normal pressure and temperature would be gas, but most of it is under such high pressure that it's probably liquid, and is still highly debated what's actually at the center.

[forrest noble]

I read today that some astronomers refer to the Jovian planets as liquid giants. I much more commonly hear them referred to as the gas & ice giants. So how recent is this change in terminology? is it widely accepted? or even correct?

Thanks for replying in advance.

Yeah, I think nothing has changed. Its just that as Aristronomer explained, the interiors of the outer planets are under enough pressure and contain enough heat that these planets should be liquid underneath their less massive atmospheres. Therefore they accordingly would more accurately be described as liquid giants even though I don't think this description will catch on in the foreseeable future since their description as gas giants is too well entrenched. Neptune and to a lesser extent Uranus might have a lot of solid ice underneath their liquid but even so an ice giant doesn't sound right because there is probably a lot of gas and liquid too.

[Hungry4info]

As I uderstand it, it is less what the phase of the matter is in that's important, and rather what composition it has. Planets that are dominantly H and He are gas giants because H and He are stereotypically gases. Volatiles like water, methane and ammonia are called "ices" in astronomical jargon and so an ice giant is simply a giant planet comprised more of these "ices."

Ultimately it just comes down to what dominates their mass. If most of the mass of the planet is made of "gases" (H, He), it's a "gas giant." If most of the mass is "ices" (volatiles), it's an "ice giant."

Composition of the giant planets of the Solar System by mass:

[forrest noble]

I think there is still a lot of speculation concerning gas, liquid, and solid states.

quote from link below:

The four solar system gas giants share a number of features in common. All have atmospheres that are mostly hydrogen and helium, and that blend into the liquid interior at pressures greater than the critical pressure, so that there is no clear boundary between atmosphere and body. They have very hot interiors, ranging from about 5000 K for Neptune to over 20,000 K for Jupiter. This great heat means that, beneath their atmospheres, the planets are most likely entirely liquid.

http://www.wordiq.com/definition/Gas_giant

[neilzero]

The old thinking was 3 states of matter and they weren't ice, gas and rock. One out of three does not win a prize. At extreme pressure and temperature we should think perhaps 5 states of matter, adding plasma and compact matter such as neutronium and white star stuff. Our four gas giant planets are about 4.6 billion years old, and they are still very hot at the center. Would you expect that 13 billion year old gas giants are cool at the center? Even at ordinary temperature and pressure we should likely add vapor which is different from gas in some respects. I agree gas predominates for Jupiter and Saturn, but I doubt there is significant ice below the cloud tops Uranus or Neptune, except for a weird definition of ice. Neil

[baric]

As I uderstand it, it is less what the phase of the matter is in that's important, and rather what composition it has. Planets that are dominantly H and He are gas giants because H and He are stereotypically gases. Volatiles like water, methane and ammonia are called "ices" in astronomical jargon and so an ice giant is simply a giant planet comprised more of these "ices."

This is how I understood it as well.

Keep in mind that the differences for ice giants are more about the gas-ice proportion. If as much H/He had been available for a developing Neptune as had been Saturn, Neptune would also be a gas giant despite having just as much ice as it does now.

[cjl]

The old thinking was 3 states of matter and they weren't ice, gas and rock. One out of three does not win a prize. At extreme pressure and temperature we should think perhaps 5 states of matter, adding plasma and compact matter such as neutronium and white star stuff. Our four gas giant planets are about 4.6 billion years old, and they are still very hot at the center. Would you expect that 13 billion year old gas giants are cool at the center? Even at ordinary temperature and pressure we should likely add vapor which is different from gas in some respects. I agree gas predominates for Jupiter and Saturn, but I doubt there is significant ice below the cloud tops Uranus or Neptune, except for a weird definition of ice. Neil

So what about a supercritical fluid?

[baric]

So what about a supercritical fluid?

And also superfluids :P

[neilzero]

I don't think there are any superfluids or super critical fluids at ordinary temperature and pressure, so we can't experience them directly. Can someone help us picture them in our mind? Ten states of matter, perhaps? Is it super critical carbon dioxide that makes an excellent cleaning fluid, warm, but under high pressure, and proposed for sequestering carbon dioxide in the deep ocean? Neil

[baric]

I don't think there are any superfluids or super critical fluids at ordinary temperature and pressure, so we can't experience them directly. Can someone help us picture them in our mind? Ten states of matter, perhaps? Is it super critical carbon dioxide that makes an excellent cleaning fluid, warm, but under high pressure, and proposed for sequestering carbon dioxide in the deep ocean? Neil

Superfluids, no. Supercritical fluids, very close.

Going down my list... Earth at 280K and 0.1MPa

Acetylene is close. 308K at 6.14MPa
Argon is closer. 151K at 4.90MPa
Carbon Monoxide... 133K at 3.50MPa

skipping to the really close:
Helium.. 5.2K at 0.227MPa
Hexaflouroethane.. 293K at .306MPa

Using your criteria, are there any examples of plasma or degenerate matter at ordinary temperatures & pressures?

[cjl]

I don't think there are any superfluids or super critical fluids at ordinary temperature and pressure, so we can't experience them directly. Can someone help us picture them in our mind? Ten states of matter, perhaps? Is it super critical carbon dioxide that makes an excellent cleaning fluid, warm, but under high pressure, and proposed for sequestering carbon dioxide in the deep ocean? Neil

Well, the post I was responding to referred to the gas giant planets as mostly gas, and I'm fairly certain that they have a much larger amount of supercritical fluid than gas...