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Exosphere From 500-1,000 km (310-620 mi; 1,600,000-3,300,000 ft) up to 10,000 km (6,200 mi; 33,000,000 ft), contain free-moving particles that may migrate into and out of the magnetosphere or the solar wind.

Exosphere - the outermost layer of the Earth's atmosphere, where atmospheric pressure and temperature are low.
Ionosphere - the atmospheric layer between the mesosphere and the exosphere; it is part of the thermosphere.

Exosphere. The outermost part of the Earth's atmosphere. It is an ill-defined, highly rareified zone which starts at a height of about 700km (435 miles) and extends into the vacuum of space.

Exosphere - The outer part of the thermosphere. Atoms and ions can escape from the exosphere directly into space ...

The exosphere is the outermost layer of the Earth's atmosphere. The exosphere goes from about 400 miles (640 km) high to about 800 miles (1,280 km).

An ~ is a super-low-density atmosphere probably formed, in this case, from atoms sputtering off Mercury's surface. The sputtering may be caused by contact with hot plasma trapped in Mercury's magnetic field.

Even in the ~, the atmosphere is still present (as can be seen for example by the effects of atmospheric drag on satellites).

Exosat satellite (Imagine the Universe Dictionary - NASA GSFC) European Space Agency's X-ray Observatory ~ (NASA Thesaurus / NASA SP-7, 1965) The outermost, or topmost, portion of the atmosphere.

~ The outermost, or topmost, portion of the atmosphere. Its lower boundary is the critical level of escape, variously estimated at 500 to 1000 kilometers above the earth's surface. Also called region of escape. See atmospheric shell.

Search for an ~ around 51 Peg B with ISO
Radiative equilibrium model of 51 Peg
Icarus, 143, 308
paper ...

~ Outermost fringe of Earth's atmosphere. expanding cosmological model exploding galaxy Galaxy in which powerful explosions are occurring in its central region and which is emitting nonthermal radiation. extinction extragalactic ...

Beyond that is the ~, where the atmosphere is so tenuous as to be space.
Highest points
Mt Everest 8848 m
Mt Everest south summit 8750 m
K2 8610 m
Kangchenjunga 8597 m
Lhotse 8511 m ...

Don't let the term "~" fool you, though. It's pressure is far lower than even the best laboratory vacuum - and it's so thin the rocket exhaust released by the Apollo landing craft nearly doubled its content!
Filed Under: Celestial Objects
First Name: ...

Mercury is surrounded by a thin envelope of gas - an ~ - containing hydrogen, helium, oxygen, sodium, potassium, calcium and magnesium. These components are not stable on long timescales so each element must have a source.

The atmospheric layers are - in order of distance from sea level - the troposphere (10 km), stratosphere (45 km), mesosphere (80 km), thermosphere (200 km), and ~ (400 km). The Mir Space Station previously orbited at 365 km above and the space shuttle orbits at 260 km.

Mercury does has a very thin atmosphere (or more correctly ~). Processes such as vaporisation of rocks by impacts, evaporation of elements from rocks, sputtering by solar wind ions or diffusion from the planet's interior contribute to it.

The presence of an ~, as it is more properly called, was confirmed by instruments on the Cassini probe which orbits the ringed planet and its moons.

Finally MESSENGER will discover the composition of Mercury's outer atmosphere (~) using an ultraviolet detector. Once compared to the surface composition it will be possible to determine which molecules entered the atmosphere from the surface and whether others entered from elsewhere.

but for Jean's escape, it's the ~ temperature that matters, and that does depend on composition, (Earth has a much higher exospheric temperature than Venus, for instance. though you wouldn't no that looking at distance to the star, or ground temperatures).

The thermosphere is the layer of the earth's atmosphere directly above the mesosphere and directly below the ~. Within this layer, ultraviolet radiation causes ionization....

Earth's atmosphere is divided up into several layers: the troposphere from about 6 - 20 kilometres up; the stratosphere from 20 - 50 kilometres; the mesosphere from 50 - 85 kilometres; the thermosphere from 85 - 690 kilometres; and the ~ out to about 10,000 kilometres.

A region in the Earth's atmosphere between the mesosphere and the ~.
third quarter moon
See last quarter moon.

The thermosphere is a thermal classification. It is the layer of the atmosphere located between the mesosphere and outer space. In the thermosphere, temperature increases with altitude. The thermosphere includes the ~ and part of the ionosphere.

The layers, troposphere, stratosphere, mesosphere, thermosphere, and the ~, vary around the globe and in response to seasonal changes. This is sometimes described as the "third atmosphere" to distinguish it from earlier atmospheric compositions.

The ~ temperature was measured at 295-355 K, 10 K lower temperatures were found from 200 to 87 km. A small magnetic field was postulated, about .0003 Earth's.

See also: See also: What is the meaning of Earth, Atmosphere, Planet, Orbit, Astro?

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