Most American scientists think an impregnable astrodome over the U.S. is sheer fantasy.
From the time.com
To his left was a window, and above him was the astrodome, used for visual signalling and also by the navigator for celestial navigation.
From the en.wikipedia.org
More examples
A transparent dome on top of an airplane where the navigator can make celestial observations
An astrodome is a hemispherical transparent dome fitted in the cabin roof of an aircraft to allow the use of a sextant during astro-navigation.
Reliant Astrodome, also known as the Houston Astrodome or simply the Astrodome, is the world's first domed sports stadium, located in Houston, Texas, USA. The stadium is part of the Reliant Park complex. ...
A transparent dome in an aeroplane fuselage through which a navigator can navigate by the stars, using a sextant.
Transparent dome, usually on dorsal surface of fuselage, to permit celestial navigation by traditional means.