Space.com: Volcanic Activity Possible on Object Beyond Neptune

In the article, they say that the presence of crystaline ice is unusual. But I don't understand how. Isn't all frozen water crystaline in nature? And if so, why is it unusual to see it? Don't comets have large amounts of water ice that remain even though they come much closer to the sun than Quaoar?

__________________
My Astrophotographs

Objects this size tend to accumulate dust and other "coatings" that mask the ice crystals. Only when impactors buldoze the coatings away or cryovolcanos spew them out over the surface, do they become visible.

__________________
It's just one of those damn things of which there are many few. -- Dan Blocker

I understand the idea that dust will prevent us from seeing the ice if it's there but the article says

What I'm not understanding is why under 279.7º F, suddenly crystaline ice can't form and what's different about the ice that could form. I'm also curious as to the detection method.

__________________
My Astrophotographs

This is just a guess, but I'm thinking this might be the opposite of what we see with the relation between crystal size and cooling time of igneous rock. Plutonic rock (subsurface rock) has larger crystals because the lavas took a longer time to cool. Lavas that a erupted onto the surface cool quicker, and have comparatively smaller crystal size. Obsidian rocks are ejected into the air and cool so rapidly that crystals fail to form, and what you get is an amorphous, "glassy" texture.

A temperature of minus 279.7 degrees Fahrenheit may be required for water to cool slowly enoguh to form a crystal lattice. If temperatures in the Kuiper Belt are much colder, water freezes much too quickly and you get an amorphous structure, instead.

__________________
I like crinoids.

I'm guessing that below that temperature, water molecules don't pack together and form the rigid lattice structure that's familiar to us -- instead they form some other lower-energy association, like an "amorphous fluff."

Intuitive guess.

Water can exist in both solid amorphous and crystalline states. To chock up another unusual property of water is that it has a lot of crystalline states, at least fourteen.

What you say is true enough but...It presumes that we have some clue what's going on out there in the first place. It could have had a collision a few million years ago that left the average temperature above -279F for several thousand years, allowing cryovolcanos to sprinkle a frozen surface with crystals.

That's just one "pulled out of the air" example. It could have a radioactive rock at its' core, keeping it warm inside, etc. & so on. I'm sure others here can provide other possibilities. The point is, when you're looking at a snow ball from 6 billion miles away, there is going to be a lot you can't see.

__________________
It's just one of those damn things of which there are many few. -- Dan Blocker

Wikipedia on ice:

__________________
0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 ...

Or you can "see" too much. Remember "steamy jungles of Venus"? Serious scientists thought Venus' perpetual cloud cover meant a tropical swamp, like Earth during Mesozoic. Which, with only a little imagination, meant dinosaurs. So logic went like this:

Can't see anything.

Therefore, dinosaurs.

Ok. I buy the "ice can have different states" deal now. But according to the article, there's not really been any labratory tests to accurately predict which state ice should be in at that distance. So if we don't really know what state it should be in, how is it surprising that it exists in one over another?

__________________
My Astrophotographs

Well, it certainly isn't in Kansas anymore.

In general terms crystal size is inversely related to the rate of cooling from the liquid to solid states.

So underground rocks cool slower than surface ones, or lave in the sea, and so have larger crystals (check out the Giant's Causeway and Fingal's Cave). If you cool fast enough crystals don't form at all, and you get an amporphous structure or "glass".

So presumably under normal conditions on Quaoar any liquid water would freeze very rapidly and not produce a significantly crystalline solid ice, and they're proposing an event that provided enough heat to allow cooling to be slow enough to allow crystals to form.

IMHO

Edited for typo

Paul. I'll buy that. But why would Quaoar have undergone a sudden cooling? What made it liquid in the first place?

__________________
My Astrophotographs

I don't think they're suggesting a sudden cooling, so much as an impact (or something) that warmed it up a bit. Enough to melt some ice to water and keep it warm enough to form crystals while cooling down again.

Perhaps I'm phrasing this wrong. If the original solidification of the object weren't sudden, then it should have normal ice crystals. Which is what is being observed. But as I understand it, with the solar nebula theory, it should have been heated by its original collapse. But that heat wouldn't have dissipated suddenly enough to cause the amorphous state of ice. So it seems to me that normal ice crystals are what we should be seeing.

__________________
My Astrophotographs

When comet Kohoutek came along it was quite bright when seen way out. This resulted in predictions that it would be very bright as it got nearer. It disappointed.
One explanation for the unusual brightness when it was way out there was that it was a virgin comet made of ice 5 or ice 6 crystalline state. This has a density much higher than normal ice. As it approached the sun it warmed enough to suddenly change state into a more normal state which made it suddenly and perhaps explosively nearly triple in size. causing a big expulsion and brightening that didn't persist.

A passing object near Q could perhaps have caused enough tidal heating to make something similar occur with very high density ice becoming more normal crystalline??? Fun to speculate.

By a virgin comet, I mean one that was making its first pass near the sun, rather than one that is in a repeating orbit.

I think it's the aging, the eventual effect of UV radiation, that produces the amorphous ice. I found this article about Pluto's companion, Charon, interesting.

I suppose the same was expected for old, quiet Quaoar. Later:

__________________
0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 ...