Earth & SkyGreek → English
Magnetosphere
/mæɡˈnitəˌsfɪr/noun
The region around a planet where its own magnetic field controls charged particles.
The Greek roots
μαγνῆτις λίθος
magnêtis líthos
Magnesian stone, lodestone
σφαῖρα
sphaîra
ball, sphere
Literally: “magnet sphere”
The story of the word
Thomas Gold named it in 1959, a year after Van Allen found the radiation belts, for the volume where Earth's field rather than the solar wind gives the orders. The magnet half comes from Magnesia, a district whose lodestone the Greeks knew and argued about; the same place name also gave magnesium and manganese, which were only separated as elements in the nineteenth century. The shape is not spherical at all: the solar wind flattens the sunward side to about ten Earth radii and draws the night side into a tail stretching past the Moon's orbit.
- How it travelled
- Ancient Greek → scientific coinage → English
- First recorded
- 1959
Same family
magnetmagnesiummanganeseatmosphere
In a sentence
Mars lost most of its atmosphere once its magnetosphere died.