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Earth's atmosphere photographed from the International Space Station.The orange and green line of airglow is at roughly the altitude of the Kármán line. [1]The Kármán line (or von Kármán line / v ɒ n ˈ k ɑːr m ɑː n /) [2] is a conventional definition of the edge of space; it is widely but not universally accepted.
Transatmospheric orbit (TAO): geocentric orbits with an apogee above 100 km and perigee that intersects with the defined atmosphere. [4] Very low Earth orbit (VLEO) is defined as altitudes between approximately 100 - 450 km above Earth’s surface. [5] [6] Low Earth orbit (LEO): geocentric orbits with altitudes below 2,000 km (1,200 mi). [7]
Pressure decreases above Earth, reaching a level at an altitude of around 19.14 km (11.89 mi) that matches the vapor pressure of water at the temperature of the human body. This pressure level is called the Armstrong line, named after American physician Harry G. Armstrong. [57] At or above the Armstrong line, fluids in the throat and lungs boil ...
Vostok 6, launched by the Soviet Union on 16 June 1963, carrying Valentina Tereshkova, was the first successful spaceflight by a woman to reach Earth orbit. Crew Dragon Demo-2, launched by SpaceX and the United States on 30 May 2020, was the first successful human spaceflight by a private company to reach Earth orbit.
Whether an object is visible depends significantly on the height above sea level from where it is observed. The Kármán line , at 100 kilometres (62 mi), is accepted by the World Air Sports Federation , an international standard-setting and record-keeping body for aeronautics and astronautics , as the boundary between the Earth's atmosphere ...
A wide variety of sources [5] [6] [7] define LEO in terms of altitude.The altitude of an object in an elliptic orbit can vary significantly along the orbit. Even for circular orbits, the altitude above ground can vary by as much as 30 km (19 mi) (especially for polar orbits) due to the oblateness of Earth's spheroid figure and local topography.
The density of the Earth's atmosphere decreases nearly exponentially with altitude. The total mass of the atmosphere is M = ρ A H ≃ 1 kg/cm 2 within a column of one square centimeter above the ground (with ρ A = 1.29 kg/m 3 the atmospheric density on the ground at z = 0 m altitude, and H ≃ 8 km the average atmospheric scale height).
2.5° by 2.5° Westerhout 5: 2.3° by 1.25° Sh2-54: 2.3° Carina Nebula: 2° by 2° Note: brightest nebula in the night sky, 1.0 apparent magnitude (V) North America Nebula: 2° by 100 ′ Earth in the Moon's sky: 2° - 1°48 ′ [12] Appearing about three to four times larger than the Moon in Earth's sky The Sun in the sky of Mercury: 1.15 ...