authalic longitude
1Latitude — This article is about the geographical reference system. For other uses, see Latitude (disambiguation). Map of Earth Longitude (λ) Lines of longitude appear vertical with varying curvature in this projection, but are actually halves of great… …
2Earth radius — The Earth s shape, like that of all major planets, approximates a sphere. A true sphere has a unique radius, but on Earth the distance from the mean sea level at each point on the surface to the center (the radius of the Earth at a point on the… …
3Map projection — A medieval depiction of the Ecumene (1482, Johannes Schnitzer, engraver), constructed after the coordinates in Ptolemy s Geography and using his second map projection A map projection is any method of representing the surface of a sphere or other …
