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The 180th meridian or antimeridian is the meridian which is 180° east or west of the Prime Meridian with which it forms a great circle. It is common to both east longitude and west longitude. It is used as the basis for the International Date Line because it for the most part passes through the open waters of the Pacific Ocean. However, the meridian passes through Russia and Fiji as well as Antarctica. Starting at the North Pole and heading south to the South Pole, the 180th meridian passes through: : The meridian also passes between (but not particularly close to): *the Gilbert Islands and the Phoenix Islands of ; *between North Island and the Kermadec Islands of ; *between the Bounty Islands and the Chatham Islands, also of . The only place where roads cross this meridian, and where there are buildings very close to it, is in Fiji. == Software representation problems == Many geographic software libraries or data formats project the world to a rectangle, very often this rectangle is split exactly at the 180th meridian. This often makes it impossible to do simple tasks (like representing an area, or a line) over the 180th meridian. Some examples: * The GeoJSON specification doesn't mention handling of the 180th meridian in its specification, as such, representations of lines crossing the 180th meridian can just as well be interpreted as going around the world. * In OpenStreetMap, areas (like the boundary of Russia) are split at the 180th meridian. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「180th meridian」の詳細全文を読む スポンサード リンク
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