To what extend can we fly up in the sky and till what level will the sky look blue?

Answer 1

The sky will gradually get blacker the higher you go since it is the earth's atmosphere which makes things look blue. The atmosphere does not end all at once, but kind of fades away.

According to Wikipedia:
http://en.wikipedia.org/wiki/Earth%27s_atmosphere

"The atmosphere has no abrupt cut-off. It slowly becomes thinner and fades away into space. There is no definite boundary between the atmosphere and outer space. Three-quarters of the atmosphere's mass is within 11 km of the planetary surface. In the United States, persons who travel above an altitude of 50.0 miles (80.5 km) are designated as astronauts. An altitude of 120 km (75 mi or 400,000 ft) marks the boundary where atmospheric effects become noticeable during re-entry."

Answer 2

Somewhere around 100,000 feet the sky looses its blue color. But of course there is no sharp cutoff, you have to make a judgment when it is black and not just dark blue any longer. The source is a picture from a balloon floating at about 100,000 feet. You be the judge.

Answer 3

Next time you fly, look straight up out your window above 20,000 feet; the sky is delightfully darker blue than you have ever seen it before.

Answer 4

Hi. SpaceShipOne flew to a height of over 100 km. The sky gets fainter and fainter until it appears to be all behind you at that height. http://www.answers.com/topic/spaceshipone