I'm trying to define a QA context about especially cold ice-worlds(maybe they should be called cryo-worlds), where surface temperature range 0-100°K. I noticed there is not a tag for ice-world, nor cryo-world, and tag description says it's reserved for cryogenic hibernation specifically. I did see the ice and dry-ice tags, although dry ice is only about 216.6 °K, and the context I was trying to get at was much colder than that. According to Wikipedia cryogenic gasses liquify at or below 123°K...

...and so I've used the cryogenics tag, I hope this is not too egregious a violation, although I was thinking I'd like to propose a couple new tags:

-absolute-zero / zero-Kelvin

(Also perhaps liquid-methane).

Quick freezing point chart

     freezing points
H2O   273.2 °K  
CO2   216.6 °K
CH4   90.70 °K
CO    68.13 °K
N2    63.15 °K

I'd rather not used tags inappropriately if at all possible, but the large discrepancy in temperatures for each of these substances is so broad, and I think could help differentiate different types of cold worlds scenarios for and Q&A.


2 Answers 2


Cryogenics is the right term for your purposes but the tag definition is incorrect.

The correct solution is perhaps to create a new cryonics tag for many of the questions currently tagged , and free up cryogenics to be used correctly.

  • 1
    $\begingroup$ I've updated Cryogenics, but not created Cryonics $\endgroup$
    – Separatrix
    Apr 4, 2019 at 12:47

There is a tag for with 97 questions so far.

This tag is for questions which are about temperature, heat and their effects on the environment, the heat of astronomical objects, living being,s things and space and what it might be like. (note: I put in an edit request to fix the commas)

While I see that also exists, I wonder if would not be sufficient.

Given that we have it makes sense to make it broader, as Separatrix did.


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