Suppose $\vec r(u,v) = \langle x(u,v), y(u,v), z(u,v)\rangle$ is a parameterization of the sphere $x^2+y^2+z^2 = \rho^2$. We may look at points on the surface of the earth corresponding to different points of the parameter domain to form an image on the $u,v$-plane. A parameterization of the sphere is therefore the data of a map projection of the globe onto a 2d-plane.
The positive $x$-axis runs through the intersection of equator and prime meridian, the positive $y$-axis is $90^\circ$ east of the positive $x$-axis, through a point in the Pacific Ocean, and the positive $z$-axis runs through the north pole.