With the advent of space navigation, scientists realized that the Earth isn't a perfect sphere—or even a perfect smooth ellipsoid. Irregularities in the Earth's mass alter its gravitational pull, which skews traditional surface measurements.
Meridians are at their widest point. One degree of longitude equals roughly 111 kilometers (69 miles) . meridian longitude
Airplanes and cargo vessels do not travel in straight lines on flat maps; they travel along "Great Circles" on a spherical Earth. Navigators use specific meridians to plot fuel-efficient paths and ensure aircraft remain safely separated in crowded international airspace. 3. Geofencing and Logistics With the advent of space navigation, scientists realized