Outer space

Outer space (also called just space) as a name for a region, refers to the relatively empty parts of the Universe, outside the atmospheres of celestial bodies. The term outer space is used to distinguish it from airspace and terrestrial locations. Although outer space is certainly spacious, it is now known to be far from empty, and filled with a tenuous plasma.

Related Topics:
Universe - Atmosphere - Airspace - Plasma

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As the Earth's atmosphere has no abrupt cut-off, but rather thins gradually with increasing altitude, there is no definite boundary between the atmosphere and space. The Federation Aeronautique Internationale has established the Kármán line at an altitide of 100 km (62 miles) as the working definition for the boundary between atmosphere and space. In the United States, persons who travel above an altitude of 50 miles (80 kilometers) are designated as astronauts. 400,000 feet (75 miles or 120 kilometers) marks the boundary where atmospheric effects become noticeable during re-entry.

Related Topics:
Earth's atmosphere - Federation Aeronautique Internationale - Kármán line - Astronauts - Re-entry

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