Where does the sky finally have its limit?

Question

Where does the sky finally have its limit?

Answer 1

That is a very good question.  There is no real 'limit' to our atmosphere.  At an altitude of 120 km ~75 miles, atmospheric effects become noticeable during re-entry.  There is such a thing as the Kármán line 100 km (62.1 miles) up that the common boundary between the atmosphere and space.  However, even here there are measurable particles from earth's atmosphere.

Hope this helps =)

Answer 2

Either the exosphere (the end of the upper atmosphere) or the edge of the universe (if you believe it's expanding). It depends on what your definition of "sky" is. You could also say the sky "ends" at the horizon, which would also be accurate.

Answer 3

The Big Bang Theory states that Universe was originally a minuscule dot of close to infinite density. Afterwards, that dot exploded, giving birth to the Universe as we know it, but according to the theory, the Universe is eternally expanding, and therefore, the sky has no limit.