# Liquid Planets? **URL:** \ **Category:** Factual Questions\ **Created:** [September 16, 2005, 1:34am UTC](https://boards.straightdope.com/t/liquid-planets/321902 "2005-09-16T01:34:48Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![yerba\_buena](https://avatars.discourse-cdn.com/v4/letter/y/7ea924/32.png) [@yerba\_buena](https://boards.straightdope.com/u/yerba_buena)\ **Post date:** [September 17, 2005, 1:02am UTC](https://boards.straightdope.com/t/liquid-planets/321902/21 "2005-09-17T01:02:17Z")
The boundary between gases and liquids becomes very blurry at high temperatures and pressures, so differentiating between them in the interiors of planets (where the pressure is very high and the temperature can be high) is essentially useless. The term for such a liquid/gas is called a “supercritical” fluid. Supercritical carbon dioxide is used in chemistry sometimes as a solvent (removing caffeine from coffee beans or dry cleaning clothes). ---
**Author:** ![Wearia](https://avatars.discourse-cdn.com/v4/letter/w/13edae/32.png) [@Wearia](https://boards.straightdope.com/u/Wearia)\ **Post date:** [September 17, 2005, 1:31am UTC](https://boards.straightdope.com/t/liquid-planets/321902/22 "2005-09-17T01:31:14Z")
> [@Q.E.D.](#): > > [Iapetus](http://www.nationmaster.com/encyclopedia/Iapetus-(moon)), a moon of Saturn, appears to be composed almost entirely of water ice. Its density of 1.1 g/cc[sup]3[/sup] appears to support this analysis. If it was closer to the Sun, it could easily be liquid. So, I have no doubt tehre _could_ be such a thing, though we currently know of none. Wait, theres water ice elsewhere in the solar system? Isn’t that one of the big things astronomers have been looking for? I’m only an amateur in my knowledge but I would have though such a discovery would be more important than in seems here. ---
**Author:** ![inkubo](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@inkubo](https://boards.straightdope.com/u/inkubo)\ **Post date:** [September 17, 2005, 1:52am UTC](https://boards.straightdope.com/t/liquid-planets/321902/23 "2005-09-17T01:52:33Z")
Our solar system is positively lousy with water! A recent article says that scientists think the asteroid Ceres may have more water than all of Earth’s oceans. Titan’s surface is mostly frozen water that has never been liquid. The Kuiper belt probably has enough water ice for reaction mass fuelling several generation ships headed towards Tau Ceti. ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [September 17, 2005, 4:09am UTC](https://boards.straightdope.com/t/liquid-planets/321902/24 "2005-09-17T04:09:20Z")
I’ve heard that another moon of Saturn’s, Enceladus, may like Iapetus be composed mostly of H20. Only, in this case it’s mostly liquid water under an ice crust, functioning approximately in the same way as lava and solidified rock work on the terrestrial planets. IIRC the water in the interior is kept liquid by tidal forces. ---
**Author:** ![snailboy](https://avatars.discourse-cdn.com/v4/letter/s/97f17d/32.png) [@snailboy](https://boards.straightdope.com/u/snailboy)\ **Post date:** [September 17, 2005, 4:30am UTC](https://boards.straightdope.com/t/liquid-planets/321902/25 "2005-09-17T04:30:10Z")
> [@Malacandra](#): > > The mantle is not liquid. After researching, I was partly wrong. Some, probably most of the mantle is solid. The asthenosphere, however, is a very viscous liquid. (Most sites call it a semi-liquid, but it does flow putting it closer to liquid in my book.) I found widely varying reports on the thickness of the asthenosphere on the Internet, but if the maximum is correct, the Earth below the crust is about 58% liquid by volume. (I doubt the crust is going to swing the value much either way.) If the minimum I’ve seen is correct, the Earth is only about 10% liquid. So what it all boils down to is that for all we know, Earth (excluding the atmosphere) could possibly be mostly liquid, but probably not. [Previous page](https://boards.straightdope.com/t/liquid-planets/321902.md?page=1)