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Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

theguardian.com

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Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#191

Post by Symmetry »

alex_duf wrote: post #177
bjo590 wrote: post #46

Earlier quoted context omitted.

No, it doesn't create a plot loop. The book explains that all of the H2O on Ceres was used to apply spin to Ceres to create artificial gravity. This is a symbol of Inner Planet's dominance over the Beleter's, because a _real_ Belter would never trade precious water for artificial gravity. This is mentioned fairly subtly in the first book, and is easy to miss while taking in the rest of the world. In addition the spin…

I had missed that Ceres' gravity is due to its spin. Does that mean humans are living upside down in their tunnels compared to Earth? And if that's the case, surely a spin that's greater than the local gravity should shatter the planet itself as the matter has no reason to stay concentrated around its core right? Am I missing something?

No. The fact that Ceres is a sphere implies that its scale is large enough for its material to behave as if it were a fluid and so reach hydrostatic equilibrium. Without serious engineering it would indeed come apart if you spun it up.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#192

Post by henearkr »

simonh wrote: post #173
henearkr wrote: post #89

Earlier quoted context omitted.

You only considered chemistry-based life. Cannot hold it against you of course. But some hard SF writers like Baxter also imagined life based on electromagnetic interactions, nuclear reactions (life in the mantle of a neutron star), fluid vortices and turbulences (life in liquid or gaseous planets), etc. Basically he included a lot of substrates that could be used to implement complexity. Also, a big drawback of sear…

Where I think most of the proposed alternate forms of life in SF fail is they focus on complexity but disregard the need to maintain order. Vortices are a good example, theres plenty of complexity there, but also a huge amount of entropy and no real way to maintain ordered, purposeful changes in structure, or isolation of function. Complexity just isn't enough, so until some of those ideas get a lot more clearly deve…

I agree those are mere plausible ideas with no real foundations, but the aim is to open our imagination to the realm of the plausible. Even those phenomena that are improbable and barely plausible, there are some of them we will encounter, and thanks to the work of sf writers we will not be too much caught off guard.

Specifically for your point on entropy and stability of vortices, I don't disagree totally though I'd like to call your attention on what is known with magnetic skyrmions. They are stable because to change spin the particles would need to overcome huge energy barriers. Then, the only difference with fluid vortices is that in a fluid there is friction that can bring the fluid elements to gradually shed their angular momentum at the contact of other elements with a different momentum. But in superfluid states that you could encounter at very low temperatures (like on some distant planet etc), it is plausible that there would exist analogous energy barriers preventing the fluid elements to directly shed their momentum! And even though, you can of course imagine fluidic circuits and rotational computations, which would have some stability thanks to the superfluid state.

Of course all of that is baseless speculation, but the point of SF is precisely to appreciate the vastness of the world of plausible phenomena...

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#193

Post by astroflask »

alexgmcm wrote: post #178
QuadrupleA wrote: post #114

Earlier quoted context omitted.

Hmm... according to wikipedia Ceres' surface is 110 - 155 Kelvin, or a toasty -262 to -181°F. https://en.m.wikipedia.org/wiki/Ceres_(dwarf_planet) Which makes sense, with little to no atmosphere. If that's correct I'm a little surprised this got voted up to top comment.

Is it possible that the conditions in the deep oceans of that world might still be amenable to life - far below the harsh surface conditions?

Yes, but the (dwarf) planet would then need some mechanism to keep the internal temperatures up, for example Europa and Enceladus have massive planets that keep their interiors warm with tidal forces, or the Pluto-Charon (practically binary) system where both bodies are very near in terms of size/mass and keep themselves warm that way.

Ceres doesn't have any companion to help in that regards, but hints of cryovolcanism have been detected (emission of water vapor on several spots), so at least _some_ internal temperature is driving volcanic processes.

Still, this isn't really my area and you should definitely consider what a planetary scientist has to say, should one chime in to this conversation.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#194

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Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#195

Post by Tepix »

austincheney wrote: post #111
gaukes wrote: post #2

Ceres is one of the more interesting candidates for life in our solar system. Ceres is in the habitable zone for our solar system (although just barely), it's surface temperature is -30 F (eq. to winter in Greenland), and it's detected that the water on the surface is 20% carbon by mass (though that can mean a lot of things).

-30F is too cold for Earth life though. Enceladus is known to have substantial warm salt water. https://en.m.wikipedia.org/wiki/Extraterrestrial_liquid_wate...

-30F (-34°C) is the surface temperature. There are probably not many people who believe that Ceres has life on its surface.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#196

Post by koheripbal »

walrus01 wrote: post #97
gaukes wrote: post #2

Ceres is one of the more interesting candidates for life in our solar system. Ceres is in the habitable zone for our solar system (although just barely), it's surface temperature is -30 F (eq. to winter in Greenland), and it's detected that the water on the surface is 20% carbon by mass (though that can mean a lot of things).

Considering that there's organisms that live at ridiculous pressures, with absolutely no sunlight and at the extreme temperatures of deep sea volcanic vents, I would not be surprised at all. https://en.wikipedia.org/wiki/Hydrothermal_vent https://en.wikipedia.org/wiki/Hydrothermal_vent_microbial_co...

Without any volcanism, it's hard to imagine there are hydrothermal vents at all.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#197

Post by Chris2048 »

QuadrupleA wrote: post #114
gaukes wrote: post #2

Ceres is one of the more interesting candidates for life in our solar system. Ceres is in the habitable zone for our solar system (although just barely), it's surface temperature is -30 F (eq. to winter in Greenland), and it's detected that the water on the surface is 20% carbon by mass (though that can mean a lot of things).

Hmm... according to wikipedia Ceres' surface is 110 - 155 Kelvin, or a toasty -262 to -181°F. https://en.m.wikipedia.org/wiki/Ceres_(dwarf_planet) Which makes sense, with little to no atmosphere. If that's correct I'm a little surprised this got voted up to top comment.

I can't see any ref to surface temp on Wikipedia, but this page: https://nineplanets.org/ceres/ says:

> Surface Temperature: -105°C

but also:

> the average surface temperature is about ... minus 38 degrees Celsius

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#198

Post by zajio1am »

lopmotr wrote: post #175
f_allwein wrote: post #151

Earlier quoted context omitted.

in case you’re wondering: That’s between -163,15 and -118,15 °C.

You really shouldn't put that 0.15 on the end. The numbers weren't that accurate to begin with so it gives the false impression that those digits mean something. I hope it doesn't feel like I'm picking on you but I can't help myself saying something because this is a pet peeve of mine. Rounding appropriately is taught in physics class at school but I think most people don't learn that or think it doesn't apply outsid…

Or perhaps one should not assume anything about accuracy just from the numeric presentation of the value and when the accuracy is relevant, it should be mentioned explicitly (or looked for in the original source). Numeric presentation is just too vague way to represent such complex issue as accuracy.

Not rounding values after conversion has an advantage that it does not change the meaning of the claim, while rounding requires evaulating assumptions of the original claim to ensure it is done properly.

Also note that rouding of intervals is different than rounding of each of its bound value separately. If the original claim is 'the value is between 110 - 155 K', then proper rounding should be -164 - -119 degC to ensure that the original inverval is inside the new interval so the meaning of the original claim (with its implicit probabilistic assumptions) still holds, just is less accurate.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#199

Post by philipswood »

philipswood wrote: post #103
at_a_remove wrote: post #48

Earlier quoted context omitted.

Numerous other ideas exist for alien life, but most of them have their shortcomings. It all boils down to chemical reactions and physics. Imagine a universe of only helium. No valence electrons would be readily available, so chances are you are not going to see helium molecules. Lithium, sure, as a metal. Continue examining various smaller (and more plentiful elements). Fluorine? Well, only one slot available, so you…

Essay by Isaac Asimov considering viable chemistries for life: "Not as we know it. The chemistry of life" http://www.bigear.org/CSMO/HTML/CS09/cs09p05.htm I was surprised to realise (that besides being N author) that he was a professor of biochemistry.

He ends up with a "list of life chemistries, spanning the temperature range from near red heat down to near absolute zero:

1. fluorosilicone in fluorosilicone 2. fluorocarbon in sulfur 3.*nucleic acid/protein (O) in water 4. nucleic acid/protein (N) in ammonia 5. lipid in methane 6. lipid in hydrogen Of this half dozen, the third only is life-as-we-know-it. Lest you miss it, I've marked it with an asterisk."

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#200

Post by zajio1am »

Twisol wrote: post #171
overflow_error wrote: post #148

Earlier quoted context omitted.

yeah but dwarf planet is not a planet, this is like saying method is a function, outrageous

If that bothers you, you'll love the nLab's page on the red herring principle :) > The mathematical red herring principle is the principle that in mathematics, a “red herring” need not, in general, be either red or a herring. > Frequently, in fact, it is conversely true that all herrings are red herrings. This often leads to mathematicians speaking of “non-red herrings,” and sometimes even to a redefinition of “herri…

Well, i usually use 'soy meat' example, which is obviously not meat. The case where adjective moves meaning outside of boundaries of original meaning, instead of just making it more precise, is kind of perverse. Perhaps people should use hyphen to make it one term in cases where the meaning is not result of composition (e.g. 'dwarf-planet' and 'soy-meat' vs. 'big planet' and 'pork meat').
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