# 180th meridian

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The 180th meridian or antimeridian [1] is the meridian 180° both east and west of the Prime Meridian, with which it forms a great circle dividing the earth into the Western and Eastern Hemispheres. It is common to both east longitude and west longitude. It mostly passes through the open waters of the Pacific Ocean, but passes across land in Russia, Fiji and Antarctica. This meridian is used as the basis for the International Date Line, but the latter deviates from it to maintain date consistency within the territories of Russia, the United States, Kiribati, Fiji and New Zealand.

A (geographic) meridian is the half of an imaginary great circle on the Earth's surface, terminated by the North Pole and the South Pole, connecting points of equal longitude, as measured in angular degrees east or west of the Prime Meridian. The position of a point along the meridian is given by that longitude and its latitude, measured in angular degrees north or south of the Equator. Each meridian is perpendicular to all circles of latitude. Each is also the same length, being half of a great circle on the Earth's surface and therefore measuring 20,003.93 km.

A great circle, also known as an orthodrome, of a sphere is the intersection of the sphere and a plane that passes through the center point of the sphere. A great circle is the largest circle that can be drawn on any given sphere. Any diameter of any great circle coincides with a diameter of the sphere, and therefore all great circles have the same center and circumference as each other. This special case of a circle of a sphere is in opposition to a small circle, that is, the intersection of the sphere and a plane that does not pass through the center. Every circle in Euclidean 3-space is a great circle of exactly one sphere.

The Western Hemisphere is a geographical term for the half of Earth which lies west of the prime meridian and east of the antimeridian. The other half is called the Eastern Hemisphere.

## Contents

Starting at the North Pole and heading south to the South Pole, the 180th meridian passes through:

The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is defined as the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface.

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

Co-ordinates
(approximate)
Country, territory or seaNotes
Arctic Ocean
Russia Chukotka Autonomous OkrugWrangel 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

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

The Gilbert Islands are a chain of sixteen atolls and coral islands in the Pacific Ocean about halfway between Papua New Guinea and Hawaii. They form the main part of Kiribati.

The Phoenix Islands or Rawaki are a group of eight atolls and two submerged coral reefs, lying in the central Pacific Ocean east of the Gilbert Islands and west of the Line Islands. They are a part of the Republic of Kiribati. During the late 1930s, they became the site of the last attempted colonial expansion of the British Empire through the Phoenix Islands Settlement Scheme. The Phoenix Islands Protected Area, established in 2008, is one of the world's largest protected areas, and home to some 120 species of coral and more than 500 species of fish.

Kiribati, officially the Republic of Kiribati, is a sovereign state in Micronesia in the central Pacific Ocean. The permanent population is just over 110,000 (2015), more than half of whom live on Tarawa Atoll. The state comprises 32 atolls and reef islands and one raised coral island, Banaba. They have a total land area of 800 square kilometres (310 sq mi) and are dispersed over 3.5 million square kilometres. Their spread straddles both the equator and the 180th meridian, although the International Date Line goes round Kiribati and swings far to the east, almost reaching the 150°W meridian. This brings the Line Islands into the same day as the Kiribati Islands. Kiribati's easternmost islands, the southern Line Islands, south of Hawaii, have the most advanced time on Earth: UTC+14 hours.

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 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. [2]
• In OpenStreetMap, areas (like the boundary of Russia) are split at the 180th meridian.

GeoJSON is an open standard format designed for representing simple geographical features, along with their non-spatial attributes. It is based on JSON, the JavaScript Object Notation.

OpenStreetMap (OSM) is a collaborative project to create a free editable map of the world. Rather than the map itself, the data generated by the project is considered its primary output. The creation and growth of OSM has been motivated by restrictions on use or availability of map information across much of the world, and the advent of inexpensive portable satellite navigation devices. OSM is considered a prominent example of volunteered geographic information.

The meridian 179° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Asia, the Pacific Ocean, the Southern Ocean, and Antarctica to the South Pole.

The meridian 179° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Asia, the Pacific Ocean, the Southern Ocean, and Antarctica to the South Pole.

A prime meridian is a meridian in a geographic coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its anti-meridian form a great circle. This great circle divides a spheroid, e.g., Earth, into two hemispheres. If one uses directions of East and West from a defined prime meridian, then they can be called the Eastern Hemisphere and the Western Hemisphere.

## Notes

1. The word antimeridian can also mean the meridian opposite to any given meridian. E.g. 20° west is the antimeridian of 160° east.
2. "RFC 7946 - The GeoJSON Format".

## Related Research Articles

Longitude, is a geographic coordinate that specifies the east–west position of a point on the Earth's surface, or the surface of a celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ). Meridians connect points with the same longitude. By convention, one of these, the Prime Meridian, which passes through the Royal Observatory, Greenwich, England, was allocated the position of 0° longitude. The longitude of other places is measured as the angle east or west from the Prime Meridian, ranging from 0° at the Prime Meridian to +180° eastward and −180° westward. Specifically, it is the angle between a plane through the Prime Meridian and a plane through both poles and the location in question.

A geographic coordinate system is a coordinate system that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are often chosen such that one of the numbers represents a vertical position and two or three of the numbers represent a horizontal position; alternatively, a geographic position may be expressed in a combined three-dimensional Cartesian vector. A common choice of coordinates is latitude, longitude and elevation. To specify a location on a plane requires a map projection.

The International Date Line (IDL) is an imaginary line of demarcation on the surface of Earth that runs from the North Pole to the South Pole and demarcates the change of one calendar day to the next. It passes through the middle of the Pacific Ocean, roughly following the 180° line of longitude but deviating to pass around some territories and island groups.

The Eastern Hemisphere is a geographical term for the half of Earth which is east of the prime meridian and west of the antimeridian. It is also used to refer to Afro-Eurasia and Australia, in contrast with the Western Hemisphere, which includes mainly North and South America. The Eastern Hemisphere may also be called the "Oriental Hemisphere". In addition, it may be used in a cultural or geopolitical sense as a synonym for the "Old World".

The Fiji Meteorological Service (FMS) is a Department of the government of Fiji responsible for providing weather forecasts and is based in Nadi. The current director of Fiji Meteorological Service is Ravind Kumar. Since 1985, FMS has been responsible for naming and tracking tropical cyclones in the Southwest Pacific region. Current Meteorologists working at FMS have a Graduate Diploma in Meteorology from the Australian Bureau of Meteorology.

The meridian 90° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, North America, the Gulf of Mexico, Central America, the Pacific Ocean, the Southern Ocean, and Antarctica to the South Pole.

The meridian 90° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Asia, the Indian Ocean, the Southern Ocean, and Antarctica to the South Pole.

The meridian 170° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Asia, the Pacific Ocean, New Zealand, the Southern Ocean, and Antarctica to the South Pole.

The meridian 175° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Asia, the Pacific Ocean, New Zealand, the Southern Ocean, and Antarctica to the South Pole.

The meridian 1° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, the Atlantic Ocean, Europe, Africa, the Southern Ocean, and Antarctica to the South Pole.

The meridian 1° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, the Atlantic Ocean, Europe, Africa, the Southern Ocean, and Antarctica to the South Pole.

This is a list of the extreme points of the Commonwealth of Nations — the points that are farther north, south, east or west, or higher or lower in elevation than any other location.

The meridian 178° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Asia, the Pacific Ocean, New Zealand, the Southern Ocean, and Antarctica to the South Pole.