ionosphere
The part of the Earth's atmosphere beginning at an altitude of about 50 kilometers (31 miles) and extending outward 500 kilometers (310 miles) or more.
Other meanings
The similar region of the atmosphere of another planet.
Where this comes from
This definition is adapted from “ionosphere” on Wiktionary, by its contributors, published under CC BY-SA 4.0. This page is published under the same licence.