<p>Recently I looked into the coldest(and hottest, but in another question) natural places. I discover this to be the Boomerang Nebula, with a freezing temperature of about −272.15 °C. Then I looked at the reason.</p>
<blockquote>
<p>The outflowing gas is moving outwards at a speed of about 164 km/s and
expanding rapidly as it moves out into space; this gas expansion
results in the nebula's unusually low temperature.</p>
<blockquote>
<p><a href="https://en.wikipedia.org/wiki/Boomerang_Nebula" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Boomerang_Nebula</a></p>
</blockquote>
<p>This allows the gas to lose its heat. It works on the same principle
as that of refrigerators where expanding gas allows cooling.</p>
<blockquote>
<p><a href="https://factslegend.org/20-interesting-boomerang-nebula-facts/" rel="nofollow noreferrer">https://factslegend.org/20-interesting-boomerang-nebula-facts/</a></p>
</blockquote>
</blockquote>
<p>Now I am sort of confused. How exactly can expanding gas lose heat, and lose it to such extent? And gas should cool to the &quot;universal surface temperature&quot;, or the cosmic microwave background temperature if it stays there. However, it cools 2 °C lower. How does this happen? Would there be bose-einstein condensate matter there?</p>

CC BY-SA 4.0
2019-03-07T00:02:01.327Z
Do you know how a refrigerator works?
ProfRob
CC BY-SA 4.0
2019-03-07T00:07:10.973Z
@RobJeffries I'm iffy on that one. I don't think I know exactly.
Max0815
CC BY-SA 4.0
2019-03-07T14:37:55.373Z
https://www.physicsforums.com/threads/why-do-gases-cool-on-expansion.470311/
Steve Linton
<temperature>
What causes cold temperature extremes?
Max0815
# What causes cold temperature extremes?

(Asked by: username_0 on 2019-03-06)

Recently I looked into the coldest(and hottest, but in another question) natural places. I discover this to be the Boomerang Nebula, with a freezing temperature of about −272.15 °C. Then I looked at the reason.

> The outflowing gas is moving outwards at a speed of about 164 km/s and
> expanding rapidly as it moves out into space; this gas expansion
> results in the nebula's unusually low temperature.
>
> > <https://en.wikipedia.org/wiki/Boomerang_Nebula>
>
> This allows the gas to lose its heat. It works on the same principle
> as that of refrigerators where expanding gas allows cooling.
>
> > <https://factslegend.org/20-interesting-boomerang-nebula-facts/>

Now I am sort of confused. How exactly can expanding gas lose heat, and lose it to such extent? And gas should cool to the "universal surface temperature", or the cosmic microwave background temperature if it stays there. However, it cools 2 °C lower. How does this happen? Would there be bose-einstein condensate matter there?

**Tags:** temperature

> **Comments:**
> **username_1**: Do you know how a refrigerator works?  
> **username_0**: @RobJeffries I'm iffy on that one. I don't think I know exactly.  
> **username_2**: https://www.physicsforums.com/threads/why-do-gases-cool-on-expansion.470311/  

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## 0 answers

