General

Used in conjunction with Mercator by some navigators to find the shortest path between two points,

Used in seismic work because seismic waves tend to travel along great circles.

Perspective (from the Earth’s centre onto a tangent plane) but not conformal, equal area, or equidistant.

Directions

True only from the centre point of projection.

Any straight line drawn on the Gnomonic map is on a great circle.

Scale

Increases rapidly away from the centre point.

Areas

Distortion increases away from the centre point.

Shapes

Distortion increases away from the centre point.

Type

Azimuthal.

Geometrically projected onto a plane. The point of projection is the centre of a globe

History

Considered to be the oldest true projection map and is ascribed to Thales, the father of abstract geometry, who lived in the sixth century B.C.

Note

Directly supported.

(United States Geological Survey, n.d.)