The Kármán line (or von Kármán line /vɒn ˈkɑːrmɑːn/) is a conventional definition of the edge of space; it is widely but not universally accepted. The international record-keeping body FAI (Fédération aéronautique internationale) defines the Kármán line at an altitude of 100 kilometres (54 nautical miles; 62 miles; 330,000 feet) above mean sea level.
While named after Theodore von Kármán, who calculated a theoretical limit of altitude for aeroplane flight at 83.8 km (52.1 mi) above Earth, the later established Kármán line is more general and has no distinct physical significance, in that there is a rather gradual difference between the characteristics of the atmosphere at the line, and experts disagree on defining a distinct boundary where the atmosphere ends and space begins. It lies well above the altitude reachable by conventional airplanes or high-altitude balloons, and is approximately where satellites, even on very eccentric trajectories, will decay before completing a single orbit.
