3-sphere two 3-balls. This construction is analogous to a construction of a 2-sphere, performed by gluing the boundaries of a pair of disks. A disk is a 2-ball, and the boundary of a disk is a circle (a 1-sphere). Let a pair of disks be of the same diameter. Superpose them and glue corresponding points on their boundaries. Again one may think of the third dimension as temperature. Likewise, we may inflate the 2-sphere, moving the pair of disks to become the northern and southern hemispheres. After removing a single point from the 2-sphere, what remains is homeomorphic to the Euclidean
Celestial Sphere Woodrow Wilson Memorial Celestial Sphere Woodrow Wilson Memorial The grounds of the Palais des Nations (seat of the United Nations Office at Geneva) contain many fine objects donated by member states of the United Nations, private sponsors and artists. The Celestial Sphere (also known as the Armillary Sphere) in the Ariana Park of the Palais des Nations is the best-known of these. The huge - over four meter diameter - "Celestial Sphere" is the chef d'oeuvre of the American sculptor Paul Manship (1885–1966). It was donated in 1939 by the Woodrow Wilson Foundation to what was then the League of Nations building. Known