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What I would like to know is Where does the spacey stuff begin and the atmospherey stuff stop ? Is it a matter of like crossing a line ?..one step forward I'm floating in space, one step back I'm enjoying friction fun ?
As the atmosphere has no abrupt cut-off, but rather thins gradually with increasing altitude, there is no definite boundary between the atmosphere and outer space. 75% of the atmosphere exists within 11 km of the planetary surface. In the United States, persons who travel above an altitude of 50 miles (80 kilometres) are designated as astronauts. The FAI defines spaceflight as over 100 km. 400,000 feet (75 miles or 120 kilometres) marks the boundary where atmospheric effects become noticeable during re-entry. The altitude of 100 kilometres or 62 miles is also frequently used as the boundary between atmosphere and space.