What is the Kármán line?
The Kármán line is the international definition for the edge of space. It is located 100 km (62 miles) above the Earth’s surface, around where the Aurora Borealis forms. The only country that takes its own alternative definition is the United States, which defines the edge of space as 50 miles (80 km) above the Earth’s surface. The international astronautics and aeronautics body which supports the Kármán line is the Fédération Aéronautique Internationale (FAI). The Kármán line idea originates with Theodore von Kármán, a Hungarian-American physicist who calculated that above around 100 km in the atmosphere, the air becomes so thin that a craft must travel at greater than orbital speed to stay aloft. This is too thin for aeronautic purposes, and as such, activity above 100km is demarcated as astronautic rather than aeronautic. Another factor is placing the Kármán line where it is is its nearness to the mesosphere-thermosphere boundary, which lies at around 85 km 53 miles). The thermosphe
