Kármán line
The Kármán line is the altitude where space begins. It is 100 km (about 62 miles) high. It commonly represents the border between the Earth's atmosphere and outer space.[1] This definition is accepted by the Fédération Aéronautique Internationale (FAI). The FAI is an international standard setting and record-keeping body for aeronautics and astronautics. The line is named after Theodore von Kármán (1881–1963), a Hungarian-American engineer and physicist. He was active in aeronautics and astronautics. He was the first to calculate that around this altitude, the atmosphere becomes too thin to support aeronautical flight. An aircraft at this altitude would have to travel faster than orbital velocity to obtain enough lift to support itself.[2] There is a sudden increase in temperature of the atmosphere and solar radiation just below the line. This places the line within the greater thermosphere.
Kármán Line Media
Earth's atmosphere photographed from the International Space Station. The orange line of airglow is at a slightly higher altitude (140–170 km) than the Kármán line.
The layers of Earth's atmosphere with the Kármán line indicated (not to scale)
Atmospheric gasses scatter blue wavelengths of visible light more than other wavelengths, giving the Earth's visible edge a blue halo. The Moon is seen behind the halo. At higher and higher altitudes, the atmosphere becomes so thin that it essentially ceases to exist. Gradually, the atmospheric halo fades into the blackness of space.
References
- ↑ S. Sanz Fernández de Córdoba (2004-06-24). "The 100 km Boundary for Astronautics". Fédération Aéronautique Internationale. Archived from the original on 2011-08-22. Retrieved 2014-05-07.
- ↑ O'Leary, Beth Laura (2009). Ann Garrison Darrin (ed.). Handbook of space engineering, archaeology, and heritage. Advances in engineering. CRC Press. p. 84. ISBN 978-1-4200-8431-3.
