# Why would a large planet with high surface pressure make water solid? **URL:** \ **Category:** Factual Questions\ **Created:** [April 14, 2015, 3:31pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645 "2015-04-14T15:31:48Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![YogSothoth](https://avatars.discourse-cdn.com/v4/letter/y/8edcca/32.png) [@YogSothoth](https://boards.straightdope.com/u/YogSothoth)\ **Post date:** [April 14, 2015, 3:31pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/1 "2015-04-14T15:31:48Z")
From [this article](http://www.slate.com/articles/health_and_science/science/2015/04/creationist_cosmology_conflicts_with_astrobiology_extraterrestrial_life.html) talking about how creationists are afraid we’ll find life on other planets. Its talking about how the earth seems perfect for sustaining life (as we know it). > [@](#): > > But there are a myriad of other factors that determine whether an exoplanet can host life. For instance, if an exoplanet is too small, it won’t be able to retain an atmosphere; if it’s too large, the high surface pressure will make water solid, regardless of the temperature. Does it mean that large mass and high gravity will compress water so its surface tension would make it solid, like glass? I’ve never heard of this before ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [April 14, 2015, 3:52pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/2 "2015-04-14T15:52:24Z")
It sounds more like creationists don’t have a solid grasp of some of the laws of physics. ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [April 14, 2015, 4:06pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/3 "2015-04-14T16:06:53Z")
> [@Ethilrist](#): > > It sounds more like creationists don’t have a solid grasp of some of the laws of physics. Wouldn’t that be true once you get to a bit below a megabar of pressure? (I don’t know how big a planet would be for this to happen.) or am I reading the water phase diagram incorrectly? ---
**Author:** ![AdamF](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/adamf/32/6246_2.png) [@AdamF](https://boards.straightdope.com/u/AdamF)\ **Post date:** [April 14, 2015, 4:19pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/4 "2015-04-14T16:19:24Z")
> [@pulykamell](#): > > Wouldn’t that be true once you get to a bit below a megabar of pressure? (I don’t know how big a planet would be for this to happen.) or am I reading the water phase diagram incorrectly? True, but if the surface pressure is 1 Mbar, there will be a point above it, where the pressure is lower and liquid water is possible. ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [April 14, 2015, 4:53pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/5 "2015-04-14T16:53:35Z")
For reference here’s a phase diagram for water [Phase diagram - Wikipedia](http://en.wikipedia.org/wiki/Phase_diagram#/media/File:Phase_diagram_of_water.svg) ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [April 15, 2015, 4:40pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/6 "2015-04-15T16:40:56Z")
The part about “if it’s too large, the high surface pressure will make water solid, regardless of the temperature.” is just another example of how devoid of knowledge of Scientific basics these people are. There are some substances where the phase change diagram is atypical, but water isn’t one of them. At any pressure you’d see on anything you’d call a planet, if it’s hot enough, you get a liquid. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [April 15, 2015, 5:12pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/7 "2015-04-15T17:12:47Z")
> [@ftg](#): > > At any pressure you’d see on anything you’d call a planet, if it’s hot enough, you get a liquid. How hot is “hot enough?” Given that the original remark was made in the context of exobiology, is “hot enough” so hot that life would be impossible? ---
**Author:** ![Your\_Great\_Darsh\_Face](https://avatars.discourse-cdn.com/v4/letter/y/ac8455/32.png) [@Your\_Great\_Darsh\_Face](https://boards.straightdope.com/u/Your_Great_Darsh_Face)\ **Post date:** [April 15, 2015, 5:25pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/8 "2015-04-15T17:25:51Z")
> [@ftg](#): > > The part about “if it’s too large, the high surface pressure will make water solid, regardless of the temperature.” is just another example of how devoid of knowledge of Scientific basics these people are. > > There are some substances where the phase change diagram is atypical, but water isn’t one of them. At any pressure you’d see on anything you’d call a planet, if it’s hot enough, you get a liquid. And, talking of knowledge of scientific basics, water in fact is a little unusual - as the pressure increases above the triple point, the melting point of water actually goes _down_ slightly. If the pressure’s right, water can exist as a liquid at about -20 Celsius. Much above 100,000 atmospheres, water is solid at all temperatures, but that would be the least of a putative lifeform’s worries. ---
**Author:** ![RedSwinglineOne](https://avatars.discourse-cdn.com/v4/letter/r/a9adbd/32.png) [@RedSwinglineOne](https://boards.straightdope.com/u/RedSwinglineOne)\ **Post date:** [April 16, 2015, 3:22pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/9 "2015-04-16T15:22:48Z")
> [@ftg](#): > > … is just another example of how devoid of knowledge of Scientific basics these people are. > … What I think is more surprising is that even given all we’ve learned about how vast and varied the universe is, people still cling to the idea that the entire universe, including an ever increasing number of exoplanets, was all created for us humans alone. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [April 16, 2015, 4:41pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/10 "2015-04-16T16:41:02Z")
> [@ftg](#): > > The part about “if it’s too large, the high surface pressure will make water solid, regardless of the temperature.” is just another example of how devoid of knowledge of Scientific basics these people are. > [@Ethilrist](#): > > It sounds more like creationists don’t have a solid grasp of some of the laws of physics. I am having trouble figuring out if that is supposed to be an indirect quote of some sort, or whether it’s the author speaking in his own voice. For those of you who found the article TL;DR here is the full paragraph for context: > [@](#): > > That’s why the Discovery Institute exudes an I-told-you-so schadenfreude whenever scientists discover exoplanets that appear to be poor candidates for sustaining life. The most basic definition of a “habitable” planet is one that exists in its solar system’s “Goldilocks zone”—close enough to its star to provide sufficient heat for liquid water but not so close that any water steams away. But there are a myriad of other factors that determine whether an exoplanet can host life. For instance, if an exoplanet is too small, it won’t be able to retain an atmosphere; if it’s too large, the high surface pressure will make water solid, regardless of the temperature. I get the feeling he is attempting to describe facts here, not quoting the Discovery Institute. ---
**Author:** ![RedSwinglineOne](https://avatars.discourse-cdn.com/v4/letter/r/a9adbd/32.png) [@RedSwinglineOne](https://boards.straightdope.com/u/RedSwinglineOne)\ **Post date:** [April 16, 2015, 6:57pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/11 "2015-04-16T18:57:54Z")
> [@CookingWithGas](#): > > I am having trouble figuring out if that is supposed to be an indirect quote of some sort, or whether it’s the author speaking in his own voice… > I get the feeling he is attempting to describe facts here, not quoting the Discovery Institute. While I couldn’t find that quote, that looks like something they would say, based on a quick look at the Discovery Institute’s website. They seem to like to argue about things like the semantics of whether or not the Sun is an “unremarkable” star. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [April 17, 2015, 9:08pm UTC](https://boards.straightdope.com/t/why-would-a-large-planet-with-high-surface-pressure-make-water-solid/717645/12 "2015-04-17T21:08:01Z")
Note that the phase diagram posted by Grey has some very hot high pressure ices up in the top right-hand corner. At about 20 Gigapascals water is ice at 650 Kelvin. Here’s an even larger diagram that goes up to 1000K, and there is still ice up in the top right, at about a hundred gigapascals. [http://www.phy.duke.edu/~hsg/363/table-images/water-phase-diagram.gif](http://www.phy.duke.edu/~hsg/363/table-images/water-phase-diagram.gif) I don’t know how high the temperature would have to be to melt the highest pressure ices, but it might be very high indeed.