Exobase definitions

Exobase

1) Atmosphere of Earth
Found on https://www.crosswordclues.com/clue/exobase

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exobase

the lower boundary of the exosphere NOTE - The height of the exobase is of the order of 500 to 600 km.
Found on http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=705-06-14

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