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Alkanen t1_j1u7dlb wrote

Reply to comment by FunkyFarmington in Meet the amateur astronomer who found a lost NASA satellite by jarvedttudd

Outer space as in outside Earth's atmosphere. That's the definition used in astronomy. Any other use is due to sci-fi authors with a bad grasp on nomenclature.

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nickh84 t1_j1u9xjk wrote

Not exactly. It's an arbitrary definition of 100km altitude. As the atmosphere doesn't exactly have an end, and outer space doesn't exactly have a start.

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ExaminationBig6909 t1_j1uldm5 wrote

It's not arbitrary, exactly. The Karman line is a theoretical point at which the atmosphere is so thin that you won't get lift from a wing. So it's a point where airplanes cannot reach.

(Also, the original calculation was for 80 km, which is used by the USAF for the boundary of space.)

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nickh84 t1_j1uodyx wrote

Its 100% arbitrary. It's a nice round number. Density is variable and 99.99% of planes r not capable of flying anywhere close to that altitude. And even above that altitude the atmosphere can produce significant drag on space craft.

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ExaminationBig6909 t1_j1uvek5 wrote

You keep using that word, I do not think it means what you think it means.

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nickh84 t1_j1xgwfh wrote

your definition can be applied at 80km. Is there any objective difference when u pass from 99km to 100km? No, there isnt. The reason 100km was used is because its a nice round number, thats purely it. It's not because planes cant fly that high, and the atmosphere extends well past 100km. The point is, its just an agreed upon number by an international group to use as a reference point and for legal reasons. Thats arbitrary. Now if u can define the precise difference between 99km and 100km, then its not arbitrary. Good luck with that tho

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dsptpc t1_j1vgdyp wrote

And to think Alan Eustace jumped out of a perfectly good balloon just above 41km. Half way to space.

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