system
Given the following post, respond as if you're commenting on Reddit:
human
Why is the Boomerang Nebula the Coldest (naturally occurring) place in the Universe?

Here is a quote from Wikipedia:
"In February 2003, the Boomerang Nebula was observed to have been releasing gases at a speed of 500,000 km/h (over 300,000 mph) for the last 1,500 years. This has cooled it down to approximately 1 K, as deduced by astronomical observation, which is the lowest natural temperature ever recorded."

Why would this lead to such a cold temperature? I understand that as energy and matter become more distant, the temperature falls as well, but shouldn't the massive amount of energy involved and the friction between particles result in an enormously hot temperature?

As you may have seen, a popular TIL brought this to my attention, and I must give credit where it is due.
gpt
That's because the gases expand as they are released. The dying star at the heart of the Boomerang Nebula squirts out a lot of gas, and these gases expand into a region of lower pressure (basically everywhere around them). It's been doing so for so long that it has reached the freezing (okay, well below freezing) temperatures we've recorded.

Why does an expanding gas cool? Simply put, gas molecules need energy to move away from each other. And this energy comes from the motion of the molecules themselves (i.e. heat), and so temperature goes down. More accurately, the gases lose energy (i.e. temperature) when they provide work (i.e. expansion).