How many miles is it to open space,outside Earth's atmosphere?

Question

How many miles is it to open space,outside Earth's atmosphere?

Answer 1

There is no clear boundary between our atmosphere and space.

The Karman line, at 100 km altitude, is commonly used to define the boundary between the Earth's atmosphere and outer space.  This is accepted by the Federation Aeronautique Internationale (FAI), which is an international standard setting and record-keeping organization for aeronautics and astronautics.

The US doesn't officially define a "boundary of space" - the American definition of an astronaut is a person who has flown above 80 km above sea level.

Answer 2

Generally satellites burn up when they enter the earth's atmosphere at around 130 km.

Answer 3

4 miles