Earth & SkyGreek → English
Thermosphere
/ˈθɜrməˌsfɪr/noun
The atmospheric layer above about 85 kilometres, where temperature rises steeply with altitude.
The Greek roots
θερμός
thermós
hot, warm
σφαῖρα
sphaîra
ball, sphere
Literally: “heat sphere”
The story of the word
Named for a temperature that would kill you if you could feel it. Sunlight strips electrons from the few molecules up there and drives them to well over 1,000°C in daylight, yet the gas is so thin that there is almost nothing to carry heat into a surface, which is why the space station orbits inside this layer without cooking. The aurora burns here too. θερμός sits inside thermometer and thermos, and reached Latin as thermae, the name for a Roman bath house.
- How it travelled
- Ancient Greek → scientific coinage → English
- First recorded
- 20th century
Same family
thermometerthermalhypothermiathermodynamics
In a sentence
Solar storms puff up the thermosphere and drag low satellites down faster.