Before revision:  A spherical drawing of a graph G is a drawing in the unit sphere S^2 in which the vertices of G are represented as points---no three on a great circle---and the edges of G are shortest-arcs in S^2 connecting pairs of vertices.
After revision:  A spherical drawing of a graph G is a drawing in the unit sphere S^2 in which the vertices of G are represented as points---no three on a great circle -- and the edges of G are shortest-arcs in S^2 connecting pairs of vertices.