An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A bounded space the surface of which has the property that if one travels in any direction upon it without changing direction, one will end up back to the departure point. An example is a sphere. Triangles which lie on the surface of a closed space will have a sum of angles which is greater than 180°. An closed space has a positive → curvature. See also → closed Universe, → open space.

→ closed; → space.