[ thur-muh-sfeer ]

  1. the region of the upper atmosphere in which temperature increases continuously with altitude, encompassing essentially all of the atmosphere above the mesosphere.

Origin of thermosphere

First recorded in 1950–55; thermo- + sphere

Words Nearby thermosphere Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use thermosphere in a sentence

  • They were piercing the thermosphere where the outside temperature gradient would zoom upward toward the 2,000 degree mark.

    First on the Moon | Jeff Sutton

British Dictionary definitions for thermosphere


/ (ˈθɜːməˌsfɪə) /

  1. an atmospheric layer lying between the mesosphere and the exosphere, reaching an altitude of about 400 kilometres where the temperature is over 1000°C

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for thermosphere


[ thûrmə-sfîr′ ]

  1. The region of the Earth's upper atmosphere lying above the mesosphere and extending from a height of approximately 80 km (50 mi) to between 550 and 700 km (341 and 434 mi) above the Earth's surface. In the thermosphere temperatures increase steadily with altitude, reaching as high as 1,727°C (3,140°F) at the highest elevations. Chemical reactions occur much faster here than on the surface of the Earth. See also exosphere mesosphere stratosphere troposphere. See illustration at atmosphere.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.