Indeed, computing the geodesic is not that simple... the geodesics are not even closed in general on Earth. I always just use GeographicLib (https://geographicl

Indeed, computing the geodesic is not that simple... the geodesics are not even closed in general on Earth. I always just use GeographicLib (https://geographiclib.sourceforge.io/ https://geographiclib.sourceforge.io/) for this. https://arxiv.org/abs/1102.1215 https://arxiv.org/abs/1102.1215 is a paper by the author on geodesics.