The Kármán line is a boundary that marks the edge of Earth's atmosphere and the beginning of space, located 62 miles (100 kilometers) above average sea level. But defining where space begins is not so straightforward, as the Earth's atmosphere does not abruptly end, but rather gradually thins out over about 600 miles. The Kármán line was named after Hungarian-American physicist Theodore von Kármán, who never actually published this idea. The Air Force, NOAA and NASA generally use 50 miles (80 kilometers) as a limit, and the Air Force gives astronaut wings to flyers who exceed this mark.
The government has been reluctant to accept a specific height; people who fly above an altitude of 60 miles (100 km) usually get astronaut wings from the Federal Aviation Administration. In a recent study, McDowell analyzed data describing the orbital paths of some 43,000 satellites collected from the North American Aerospace Defense Command (NORAD). Kármán made the necessary calculations and then rounded up the answer to that memorable figure of 100 kilometers (62 miles). In addition to the space limit line, von Kármán is associated with a series of engineering equations, laws, constants and aerospace designs, as well as with some awards in this field.
In the early 1960s, Haley applied the von Kármán criteria more specifically, determining that the real limit of space was about 52 miles (84 km) above the ground. Now that Virgin Galactic appears to be about to launch paying passengers on suborbital trajectories, many people are wondering if those lucky space tourists will earn their astronaut wings. Von Kármán's original work emerged from a debate at a conference, but the first comprehensive publications on the limits of space were made by Andrew Gallagher Haley, the world's first professional in space law. Traveling beyond the confines of Earth's atmosphere would take you about 6,000 miles (10,000 km) above the Earth's surface to the top of the highest layer of Earth's atmosphere, the exosphere.
