2. Latitude and Longitude The latitude and longitude system was developed in the middle ages. Ptolemy also used a grid system in ancient Greece. Latitude lines run horizontally and are also known as parallels. Longitude lines, also known as meridians, run vertically.
21. International Date Line Ferdinand Magellan and crew in 1519 set out on their westward journey from Spain to circumnavigate the Earth. Upon their return three years later, they discovered that their meticulously kept logs were off by one day. This was one of the first recorded experience with changing global time. This earlier experience would ultimately lead to the establishment of the international date line. The International Date Line lies directly opposite of the prime meridian and having a longitude of 180°. Crossing the line when traveling east one turns their calendar back a full day. Traveling west one moves their calendar forward one day.
