The Collaborative International Dictionary of English v.0.48:

Cosmosphere \Cos"mo*sphere\ (k[o^]z"m?-sf?r), n. [Gr. ko`smos
   the world + E. sphere.]
   An apparatus for showing the position of the earth, at any
   given time, with respect to the fixed stars. It consist of a
   hollow glass globe, on which are depicted the stars and
   constellations, and within which is a terrestrial globe.
   [1913 Webster]