The 180th meridian or antimeridian is the meridian 180° both east and west of the prime meridian in a

geographical coordinate system The geographic coordinate system (GCS) is a spherical or ellipsoidal coordinate system for measuring and communicating positions directly on the Earth as latitude and longitude. It is the simplest, oldest and most widely used of the vario ...

. The

longitude Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek let ...

at this line can be given as either east or west. On

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

, these two meridians form a great circle that divides the earth into the Western and Eastern Hemispheres. The antimeridian mostly passes through the open waters of the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...

, but also across land in

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...

Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consis ...

, and

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

. An important function of this meridian is its use as the basis for the International Date Line, which snakes around national borders to maintain date consistency within the territories of Russia, the United States, Kiribati, Fiji and New Zealand. Starting at the

North Pole The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface. It is called the True North Pole to distinguish from the Ma ...

of the Earth and heading south to the

South Pole The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies antipod ...

, the 180th meridian passes through: TodayYesterday

The meridian also passes between (but not particularly close to): *through the Aleutian Island chain of US territory *the Gilbert Islands and the Phoenix Islands of

Kiribati Kiribati (), officially the Republic of Kiribati ( gil, ibaberikiKiribati),Kiribati
''The Wor ...

* North Island and the Kermadec Islands of

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...

*the

Bounty Islands The Bounty Islands ( mi, Moutere Hauriri; "Island of angry wind") are a small group of 13 uninhabited granite islets and numerous rocks, with a combined area of , in the South Pacific Ocean. Territorially part of New Zealand, they lie about e ...

and the

Chatham Islands The Chatham Islands ( ) (Moriori: ''Rēkohu'', 'Misty Sun'; mi, Wharekauri) are an archipelago in the Pacific Ocean about east of New Zealand's South Island. They are administered as part of New Zealand. The archipelago consists of about t ...

, also of New Zealand The only places where roads cross this meridian are in Fiji and Russia. Fiji has several such roads and some buildings very close to it - and Russia has
single dirt road

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 non-trivial to do simple tasks (like representing an area, or a line) over the 180th meridian. Some examples: * The GeoJSON specification strongly suggests splitting geometries so that neither of their parts cross the antimeridian. * In OpenStreetMap, areas (like the boundary of Russia) are split at the 180th meridian.

Notes

{{Time measurement and standards m180 meridian Pacific Ocean

Software representation problems

See also

Notes