thermosphere

noun ther·mo·sphere \ ˈthər-mə-ˌsfir \

Definition of thermosphere

: the part of the earth's atmosphere that begins at about 50 miles (80 kilometers) above the earth's surface, extends to outer space, and is characterized by steadily increasing temperature with height

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thermospheric

play \ˌthər-mə-ˈsfir-ik, -ˈsfer-\ adjective

Recent Examples of thermosphere from the Web

The goal is to figure out the particle makeup of the thermosphere and ionosphere, known as the neutral atmosphere and map its changing temperatures.

— richard tribou, OrlandoSentinel.com, "NASA hitches ride on commercial satellite for UCF-led atmosphere study," 26 Jan. 2018
Richard Branson licensed the technology for Virgin Galactic, his space tourism gambit, which aims to start regular visits to the thermosphere by 2012.

— carl hoffman, WIRED, "Virgin Galactic’s Space-Grazing Aircraft Is Ready for Liftoff," 15 Nov. 2009

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'thermosphere.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.