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In the exosphere, beginning at about 600 km (375 mi) above sea level, the atmosphere turns into space, although, by the judging criteria set for the definition of the Kármán line (100 km), most of the thermosphere is part of space. The border between the thermosphere and exosphere is known as the thermopause.
It is located directly above the thermosphere. Very little is known about it due to a lack of research. Mercury, the Moon, Ceres, Europa, and Ganymede have surface boundary exospheres, which are exospheres without a denser atmosphere underneath. The Earth's exosphere is mostly hydrogen and helium, with some heavier atoms and molecules near the ...
As a lower boundary for the exosphere this boundary is also called the exobase. [1] The exact altitude varies by the energy inputs of location, time of day, solar flux, season, etc. and can be between 500 and 1,000 kilometres (310 and 620 mi) high at a given place and time because of these. A portion of the magnetosphere dips below this layer ...
Because the thermopause lies at the lower boundary of the exosphere, it is also referred to as the exobase. The lower part of the thermosphere, from 80 to 550 kilometres (50 to 342 mi) above Earth's surface, contains the ionosphere.
Exosphere – The outermost layer of an atmosphere; Exobase – The lower boundary of the exosphere; Thermopause – The upper boundary of the thermosphere; Thermosphere – The layer of the atmosphere above the mesosphere and below the exosphere; Mesopause – The temperature minimum at the boundary between the mesosphere and the thermosphere
The exosphere, which on Earth lies between the altitudes of about 700 kilometres (435 mi) and 10,000 kilometres (6,200 mi) The ionosphere, an ionized portion of the upper atmosphere which includes the upper mesosphere, thermosphere, and lower exosphere and on Earth lies between the altitudes of 48 and 965 kilometres (30 and 600 mi)
Terrestrial aeronomy focuses on the Earth's upper atmosphere, which extends from the stratopause to the atmosphere's boundary with outer space and is defined as consisting of the mesosphere, thermosphere, and exosphere and their ionized component, the ionosphere. [5]
Between the Viking and Mars Global Surveyor missions, Mars saw "Much colder (10-20 K) global atmospheric temperatures were observed during the 1997 versus 1977 perihelion periods" and "that the global aphelion atmosphere of Mars is colder, less dusty, and cloudier than indicated by the established Viking climatology," [8] with "generally colder ...