Earth-centered, Earth-fixed is a cartesian spatial reference system that represents locations in the vicinity of the Planet (including its surface, interior, atmosphere, and surrounding outer space) as X, Y, and Z measurements from its center of mass.

The Mercator projection is a cylindrical map projection presented
by Flemish geographer and cartographer Gerardus Mercator in 1569.
It became the standard map projection for navigation because of
its unique property of representing any course of constant bearing
as a straight segment.