[stametseater]

"Edge of space" is a pretty loosey-goosey expression. For instance:

"What it takes to fly spy plane U-2 to the edge of space" https://www.bbc.com/future/article/20140224-flying-at-the-ed...

(The U-2 flies at something around 21 to 25 kilometers, depending on what source you go by.)

[wongarsu]

Interesting. Apparently some people consider the Armstrong Line [1] (where pressure is low enough that water boils at body temperature, at about 18km) to be the start of "near space". As opposed to "outer space" which starts at the Kármán line at 100km (unless you are in the US, where outer space starts at 50miles/80km instead)

1: https://en.wikipedia.org/wiki/Armstrong_limit

[jackmott42]

It is a normal human thing to make categories when nature is like "nah we got a continuous spectrum here y'all" and then humans argue about the categories forever.

Mammals, animals that give birth to live young, have fur. Monotremes say wat!!?

[DoreenMichele]

TIL:

https://en.m.wikipedia.org/wiki/Monotreme