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The mesopause, at an altitude of 80–90 km (50–56 mi), separates the mesosphere from the thermosphere—the second-outermost layer of Earth's atmosphere. On Earth, the mesopause nearly co-incides with the turbopause, below which different chemical species are well-mixed due to turbulent eddies.
The troposphere is the lowest layer of Earth's atmosphere. It extends from Earth's surface to an average height of about 12 km (7.5 mi; 39,000 ft), although this altitude varies from about 9 km (5.6 mi; 30,000 ft) at the geographic poles to 17 km (11 mi; 56,000 ft) at the Equator, [17] with some variation due
Hubble Space Telescope [41] 2 July 1990: First time a spacecraft coming from deep space uses the Earth for a gravity-assist manoeuvre. ESA Giotto [42] 21 October 1991: First asteroid flyby (951 Gaspra closest approach 1,600 km). USA (NASA) Galileo: 1992 First confirmed observation of an exoplanet. Canada Poland: Aleksander Wolszczan & Dale ...
Being above the atmosphere in particular and Earth's magnetic field gives access to the solar wind and infrared and ultraviolet radiations that cannot reach Earth's surface. The Sun generates most space weather , which can affect power generation and transmission systems on Earth and interfere with, and even damage, satellites and space probes.
The layers are to scale. From the Earth's surface to the top of the stratosphere (50km) is just under 1% of Earth's radius. The exosphere is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the density is so low that the molecules are essentially collision ...
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).
Also, out of about 340 W/m 2 of reflected shortwave (105 W/m 2) plus outgoing longwave radiation (235 W/m 2), 80-100 W/m 2 exits to space through the infrared window depending on cloudiness. About 40 W/m 2 of this transmitted amount is emitted by the surface, while most of the remainder comes from lower regions of the atmosphere. In a ...
This was 8 km (5 mi) higher than predicted, and the time of the closest approach was within a second of the prediction. It was the first time that a deep space probe had returned to Earth from interplanetary space. [62] A second flyby of Earth was at 304 km (189 mi) at 15:09:25 UTC on December 8, 1992. [82]