The significant digits! They burn!
I can’t believe you forgot the adage:
Two-four-one-point-three, oxygen glows green.
Two-four-one-point-five, glows red like a fire.
They are astronomers, they calculated the height in metric units. The fact that the threshold works out to exactly .15 kilomiles is a coincidence. /s
For those like me wondering why oxygen emission depends on altitude, it’s that the excited lifetime is very long for red, so it tends to decay via collisions at lower altitudes.
TIL, there’s oxygen molecules above 240Km. I thought there’s hardly anything above 100Km and that’s why they set it as the lowest boundaries of space.
There is hardly anything. However, there’s never nothing. The atmosphere is a thin and continuously decreasing thing, but there’s no point where it stops. Space is nearly a vacuum, but technically not totally. It’s close enough that we normally say it is, but there are particles bouncing around.
It’s cute the atomic oxygen is excitied, too <3
Is this color difference related to Rayleigh scattering? i.e. the reason why the sky is blue, and why sunsets are red?
