180th meridian

"Anti-Meridian" redirects here. For the Brave Saint Saturn album, see Anti-Meridian (album).

For ante meridiem (AM), the time before midday, see 12-hour clock.

180th meridian

The International Date Line zigzags around the 180th Meridian.

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:

Co-ordinates (approximate)	Country, territory or sea	Notes
	Arctic Ocean
	Russia	Chukotka Autonomous Okrug — Wrangel Island
	Chukchi Sea
	Russia	Chukotka Autonomous Okrug
	Bering Sea
	Amchitka Pass	Passing just east of Semisopochnoi Island, Alaska, United States (at )
	Pacific Ocean	Passing just east of Nukulaelae atoll, Tuvalu (at ) Passing just west of the island of Cikobia, Fiji (at )
	Fiji	Islands of Vanua Levu, Rabi, and Taveuni
	Pacific Ocean	Passing just east of the island of Moala, Fiji (at ) Passing just west of the island of Totoya, Fiji (at ) Passing just east of the island of Matuku, Fiji (at )
	Southern Ocean
	Antarctica	Ross Dependency, claimed by New Zealand

180° Meridian, Taveuni, Fiji

The meridian also passes between (but not particularly close to):

• the Gilbert Islands and the Phoenix Islands of Kiribati;
• between North Island and the Kermadec Islands of New Zealand;
• between the Bounty Islands and the Chatham Islands, also of New Zealand.

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.

See also

• 179th meridian east
• 179th meridian west