Orthographic globe map: how country sizes change

Orthographic projection: key facts and what it does to country sizes

Distortion class: Neither equal-area nor conformal
Graticule type: Perspective azimuthal
Creator: Ancient Greeks (used by Hipparchus, among others)
Year: 2nd century BC
Area: Distorted; only the center is free of distortion, and areas are compressed more and more toward the edge of the disk
Shape: Highly distorted near the edges (foreshortened perspective)
Distances: Distorted: distances measured from the center shrink toward the edge of the disk
Angles and directions: Distorted; only the center of the map is free of distortion

The orthographic projection shows the Earth as it looks from very far away, so it holds only one hemisphere at a time. When the map opens, the globe faces the point where the equator meets the prime meridian. Of the thirty Tissot indicatrices, only ten are then fully visible, those at 30° east and west. The ones at 90° lie on the very rim of the disk, and those at 150° are on the far side.

This projection enlarges nothing. Everything farther from the center of the disk is foreshortened toward the rim, while the dimension along the rim stays true. The ellipses near the equator are therefore 13% narrower, and those at 60° latitude are squashed to about 43%. The foreshortening depends only on distance from the center: 50% remains at a distance of 60°, 31% at 72° and 17% at 80°. In the opening view Greenland lies about 76° from the center of the disk and is squashed to less than a quarter, so it looks like a narrow strip despite covering more than 2 million km².

Add your first country, Poland for example, and the globe turns by itself to put it in the middle. There its outline has its true shape. Drag it toward the rim: 72° from the center it is squashed toward the rim to roughly a third, and right next to the rim it turns into a thin sliver. On azimuthal maps with the same center, the equidistant and the gnomonic, areas near the edge expand, while here they shrink. The Tissot indicatrices disappear while you rotate the globe and return when you let go.

Full guide: Orthographic projection Compare with another projection Quiz: name the projection Empires at true scale

Orthographic globe map: frequently asked questions

Why does Greenland look like a thin strip on the globe map?

In the starting view it lies about 76° from the center of the disc, and the orthographic projection foreshortens everything toward the edge. Greenland is flattened to less than a quarter, though it covers over 2 million km².

How much of the Earth can I see on the orthographic globe?

Only one hemisphere at a time. On opening, the globe faces the point where the equator meets the prime meridian, and of the thirty Tissot ellipses ten are fully visible. The ellipses at 150° longitude are on the far side.

How do I see a country in its true shape on the globe?

Add it to the map: the globe turns by itself to put the country in the middle, where its outline has its true shape. Dragged toward the edge it starts to flatten, and at 72° from the center about a third remains.

Does the orthographic projection enlarge anything?

No, it only foreshortens. The dimension along the edge stays true, while toward the edge 50% remains at 60° from the center, 31% at 72° and 17% at 80°. The opposite of the azimuthal equidistant and gnomonic maps.