Earth Coordinates, Equator vs Pole & Solstice Calculator

Lines of latitude are always about 111 km per degree apart, but lines of longitude converge toward the poles, so the distance covered by one degree of longitude is 111.32 km × cos(latitude). At Perth's latitude of about 31.95°S, cos(31.95°) = 0.849, so one degree of longitude is about 94.5 km. At the equator it is the full 111.32 km, and at the poles it falls to zero. Use this to convert a difference in longitude to a ground distance, or to estimate how far east or west a position is. For precise navigation use the great-circle formula or the WGS84 ellipsoid, because the simple cosine rule treats the Earth as a sphere.