If you just want nearest neighbor, I would recommend storing floating point (x, y, z) coordinates, and using Euclidean distance in 3-space. (Or rather, the squa

If you just want nearest neighbor, I would recommend storing floating point (x, y, z) coordinates, and using Euclidean distance in 3-space. (Or rather, the square of distance Δx² + Δy² + Δz²; skip the square root.) If you want to save storage space / bandwidth, you can use the stereographic projection onto a plane and then cut the precision of the floating-point numbers. Stereographic projection / inverse stereographic projection only requires 1 division per point. Latitude/longitude is quite an inefficient and cumbersome way of representing points on a sphere, though it’s convenient if navigating using the stars.