angle antipodes automotive navigation system bordeaux circle of latitude earth earth ellipsoid ellipse ellipsoid equator geocode geodetic system geographic coordinate conversion geographic information system geoid geotagging global positioning system great-circle distance greenwich helmert transformation ice age kde kstars latitude linux longitude map projection metre newlyn prime meridian quito rotation saint petersburg scandinavia scotland sea level semi-major axis semi-minor axis sphere spherical trigonometry translation tropic of cancer tropic of capricorn united kingdom united states universal transverse mercator coordinate system