exosphere

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ex·o·sphere

 (ĕk′sō-sfîr′)
n.
1. The outermost region of a planet's atmosphere.
2. The outermost region of the earth's atmosphere, lying above the thermosphere and extending thousands of kilometers into space, from which molecules having sufficient velocity can escape the earth's gravitation.

ex′o·spher′ic (-sfîr′ĭk, -sfĕr′-) adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

exosphere

(ˈɛksəʊˌsfɪə)
n
(Physical Geography) the outermost layer of the earth's atmosphere. It extends from about 400 km above the earth's surface
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

ex•o•sphere

(ˈɛk soʊˌsfɪər)

n.
the highest region of the atmosphere.
[1950–55]
ex`o•spher′ic (-ˈsfɛr ɪk, -ˈsfɪər-) adj.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.

ex·o·sphere

(ĕk′sō-sfîr′)
The outermost region of the Earth's atmosphere, lying beyond the ionosphere and extending indefinitely into space. The air in the exosphere gets thinner and thinner until the lightest particles, such as hydrogen atoms, begin to escape Earth's gravity.
The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

exosphere

the highest portion of the earth’s atmosphere, from which air molecules can escape into space. Cf. ionosphere.
See also: Atmosphere
-Ologies & -Isms. Copyright 2008 The Gale Group, Inc. All rights reserved.

exosphere

The outermost layer of the atmosphere of a planet.
Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.exosphere - the outermost atmospheric layer
layer - a relatively thin sheetlike expanse or region lying over or under another
atmosphere - the envelope of gases surrounding any celestial body
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
Translations
exosphère
References in periodicals archive ?
Among their topics are the thermal and orbital evolution of Enceladus: observational constraints and models, Saturn's diffuse E Ring and its connection with Enceladus, Saturn's other icy moons: geographically complex worlds in their own right, exospheres and magnetospheric currents at Saturn's icy moons: Dione and Rhea, and Enceladus astrobiology: habitability and the origin of life.