Ever since it was discovered that the Earth is round, cartographers and mariners have struggled with how to project the spherical globe onto a two-dimensional chart. The variations are plentiful and the history is fascinating (if you're fascinated by that sort of thing!) The result is an inevitable distortion of some areas of the globe.
Note
To learn more about map projections and spherical distortions, visit http://en.wikipedia.org/wiki/Map_projection.
As a computer graphics designer, it's perhaps a little less mysterious than it was to ancient mariners because we know about UV Texture mapping.
3D computer models in Unity are defined by meshes—a set of Vector3 points connected with edges, forming triangular shaped facets. You can unwrap a mesh (in Blender, for instance) into a flattened 2D configuration to define the mapping of texture pixels to the corresponding areas on the mesh surface (the UV coordinates). A globe of the Earth, when unwrapped, will be distorted...
