Something like 99.6% of the atmosphere is below you at 100,000 feet. This is what matters, not the fact you're in space, but the fact you're not looking through a hot(ish) dense gas filled with moisture.

That's still equivalent to an martian atmosphere above.

Except thay the mars atmosphere contains considerable amoints of dust and weather. Earth's atmosphere at these altitudes is bone dry and homogeneous. Presssures may be similar but the optical properties are totally different.

Still good enough to take some great infrared pictures. Sure, it’s not even close to the same league as JWST, but most astronomers on the planet are jumping over each other to submit proposals for observation on that.

That is an interesting note, but I’m not sure how much intuition it adds. Mars somewhat famously have not a ton of atmosphere, right?

Yes, both are very thin indeed, Mars has 6-10 millibars vs 1013 millibars at Earth sea level.

Who cares, given that for a telescope what matters is the fraction of the atmosphere below it and that it is viewing things that are for all practical purposes at infinity it might as well be in space, the images wouldn't be any different unless the angle was very oblique, and even then the difference between being on the ground and being truly in space would be rather smaller for the second.

"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.)

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

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!!?

TIL:

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

For others, the definition is generally https://en.m.wikipedia.org/wiki/Kármán_line

“Edge” is doing a lot of work here, haha. In fact, a paper airplane has flown higher than this balloon!

Only after it was dropped from an even higher altitude. You could also do it with a rock.

I too did a quick return to "Space Elevator"!

https://news.ycombinator.com/item?id=35629972