page_title: Kármán line
hierarchical_section_title: Kármán line
caption_attribution_description: English: A dark blue shaded diagram subdivided by horizontal lines, with the names of the five atmospheric regions arranged along the left. From bottom to top, the troposphere section shows Mount Everest and an airplane icon, the stratosphere displays a weather balloon, the mesosphere shows meteors, and the thermosphere includes an aurora and the Space Shuttle. At the top, the exosphere shows only stars., Updating File:Atmosphere layers-en.svg caricature, replacing Space Shuttle with International Space Station. Atmospheric density through the lowest two layers is overlaid so as to show how much atmosphere is found at what altitudes.
context_page_description: The Kármán line is an attempt to define a boundary between Earth's atmosphere and outer space. This is important for legal and regulatory measures; aircraft and spacecraft fall under different jurisdictions and are subject to different treaties.
  The World Air Sports Federation, an international standard-setting and record-keeping body for aeronautics and astronautics, defines the Kármán line as the altitude of 100 kilometres above Earth's mean sea level. Other organizations do not use this definition. For instance, the US Air Force and NASA define the limit to be 50 miles above sea level. There is no international law defining the edge of space, and therefore the limit of national airspace.
  The line is named after Theodore von Kármán, a Hungarian American engineer and physicist, who was active primarily in aeronautics and astronautics. He was the first person to calculate the altitude at which the atmosphere becomes too thin to support aeronautical flight and arrived at 83.6 km himself. The reason is that a vehicle at this altitude would have to travel faster than orbital velocity to derive sufficient aerodynamic lift to support itself.
context_section_description: The Kármán line is an attempt to define a boundary between Earth's atmosphere and outer space. This is important for legal and regulatory measures; aircraft and spacecraft fall under different jurisdictions and are subject to different treaties.
  The World Air Sports Federation (FAI), an international standard-setting and record-keeping body for aeronautics and astronautics, defines the Kármán line as the altitude of 100 kilometres (62 miles; 330,000 feet) above Earth's mean sea level. Other organizations do not use this definition. For instance, the US Air Force and NASA define the limit to be 50 miles (80 km) above sea level. There is no international law defining the edge of space, and therefore the limit of national airspace.
  The line is named after Theodore von Kármán (1881–1963), a Hungarian American engineer and physicist, who was active primarily in aeronautics and astronautics. He was the first person to calculate the altitude at which the atmosphere becomes too thin to support aeronautical flight and arrived at 83.6 km (51.9 miles) himself. The reason is that a vehicle at this altitude would have to travel faster than orbital velocity to derive sufficient aerodynamic lift to support itself. The line is approximately at the turbopause, above which atmospheric gases are not well-mixed.  The mesopause atmospheric temperature minimum has been measured to vary from 85 to 100 km, which places the line at or near the bottom of the thermosphere.
caption: The Kármán line lies within the lower thermosphere (not to scale)[1]
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