Western Hemisphere

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The Western Hemisphere

The Western Hemisphere is a geographical term [1] [2] for the half of Earth which lies west of the prime meridian (which crosses Greenwich, London, United Kingdom) and east of the antimeridian. The other half is called the Eastern Hemisphere. [3]

Geography The science that studies the terrestrial surface, the societies that inhabit it and the territories, landscapes, places or regions that form it

Geography is a field of science devoted to the study of the lands, features, inhabitants, and phenomena of the Earth and planets. The first person to use the word γεωγραφία was Eratosthenes. Geography is an all-encompassing discipline that seeks an understanding of Earth and its human and natural complexities—not merely where objects are, but also how they have changed and come to be.

Earth Third planet from the Sun in the Solar System

Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.

West one of the four cardinal directions

West is one of the four cardinal directions or points of the compass. It is the opposite direction from east.



The Western Hemisphere consists of the Americas, the western portions of Eurasia and Africa, the extreme eastern tip of Siberia (Russia), numerous territories in Oceania, and a portion of Antarctica, while excluding some of the Aleutian Islands to the southwest of the Alaskan mainland.

Americas landmass comprising the continents of North America and South America

The Americas comprise the totality of the continents of North and South America. Together, they make up most of the land in Earth's western hemisphere and comprise the New World.

Eurasia The combined continental landmass of Europe and Asia

Eurasia is the combined continental landmass of Europe and Asia. The term is a portmanteau of its constituent continents. Located primarily in the Northern and Eastern Hemispheres, it is bordered by the Atlantic Ocean to the west, the Pacific Ocean to the east, the Arctic Ocean to the north, and by Africa, the Mediterranean Sea, and the Indian Ocean to the south. The division between Europe and Asia as two different continents is a historical social construct, with no clear physical separation between them; thus, in some parts of the world, Eurasia is recognized as the largest of the six, five, or even four continents on Earth. In geology, Eurasia is often considered as a single rigid megablock. However, the rigidity of Eurasia is debated based on paleomagnetic data.

Africa The second largest and second most-populous continent, mostly in the Northern and Eastern Hemispheres

Africa is the world's second largest and second most-populous continent. At about 30.3 million km2 including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area. With 1.2 billion people as of 2016, it accounts for about 16% of the world's human population. The continent is surrounded by the Mediterranean Sea to the north, the Isthmus of Suez and the Red Sea to the northeast, the Indian Ocean to the southeast and the Atlantic Ocean to the west. The continent includes Madagascar and various archipelagos. It contains 54 fully recognised sovereign states (countries), nine territories and two de facto independent states with limited or no recognition. The majority of the continent and its countries are in the Northern Hemisphere, with a substantial portion and number of countries in the Southern Hemisphere.

In an attempt to define the Western Hemisphere as the parts of the world which are not part of the Old World, there also exist projections which use the 20th meridian west and the diametrically opposed 160th meridian east to define the hemisphere. [1] This projection excludes the European and African mainlands and a small portion of northeast Greenland, but includes more of eastern Russia and Oceania.

Old World collectively Africa, Europe, and Asia

The term "Old World" is used commonly in the West to refer to Africa, Asia and Europe, regarded collectively as the part of the world known to its population before contact with the Americas and Oceania. It is used in the context of, and contrasts with, the New World.

20th meridian west

The meridian 20° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Greenland, Iceland, the Atlantic Ocean, the Southern Ocean, and Antarctica to the South Pole. The 20th meridian west forms a great circle with the 160th meridian east.

160th meridian east

The meridian 160° 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 center of the Western Hemisphere is located in the Pacific Ocean at the intersection of the 90th meridian west and the Equator, among the Galápagos Islands. The nearest land is Genovesa Island at 0°19′00″N89°57′00″W / 0.316667°N 89.95°W / 0.316667; -89.95 .

Pacific Ocean Ocean between Asia and Australia in the west, the Americas in the east and Antarctica or the Southern Ocean in the south.

The Pacific Ocean is the largest and deepest of Earth's oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south and is bounded by Asia and Australia in the west and the Americas in the east.

90th meridian west meridian

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.

Equator Intersection of a spheres surface with the plane perpendicular to the spheres axis of rotation and midway between the poles

An equator of a rotating spheroid is its zeroth circle of latitude (parallel). It is the imaginary line on the spheroid's surface, equidistant from its poles, dividing it into northern and southern hemispheres. In other words, it is the intersection of the spheroid's surface with the plane perpendicular to its axis of rotation and midway between its geographical poles.

The highest mountain in the Western Hemisphere is Aconcagua in the Andes of Argentina at 6,960.8 metres (22,837 ft). [4]

Aconcagua highest mountain in South America(6962 m)

Aconcagua, with a summit elevation of 6,960.8 metres (22,837 ft), is the highest mountain in both the Southern and Western Hemispheres. It is located in the Andes mountain range, in the Mendoza Province, Argentina, and lies 112 km (70 mi) northwest of its capital, the city of Mendoza, about five km (3.1 mi) from San Juan Province and 15 km (9.3 mi) from the international border with Chile. The mountain itself lies entirely within Argentina, immediately east of Argentina's border with Chile. Its nearest higher neighbor is Tirich Mir in the Hindu Kush, 16,520 kilometres (10,270 mi) away. It is one of the Seven Summits.

Andes mountain range running along the tu mamide of South America

The Andes or Andean Mountains are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. This range is about 7,000 km (4,300 mi) long, about 200 to 700 km wide, and of an average height of about 4,000 m (13,000 ft). The Andes extend from north to south through seven South American countries: Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile and Argentina.

Argentina federal republic in South America

Argentina, officially named the Argentine Republic, is a country located mostly in the southern half of South America. Sharing the bulk of the Southern Cone with Chile to the west, the country is also bordered by Bolivia and Paraguay to the north, Brazil to the northeast, Uruguay and the South Atlantic Ocean to the east, and the Drake Passage to the south. With a mainland area of 2,780,400 km2 (1,073,500 sq mi), Argentina is the eighth-largest country in the world, the fourth largest in the Americas, and the largest Spanish-speaking nation. The sovereign state is subdivided into twenty-three provinces and one autonomous city, Buenos Aires, which is the federal capital of the nation as decided by Congress. The provinces and the capital have their own constitutions, but exist under a federal system. Argentina claims sovereignty over part of Antarctica, the Falkland Islands, and South Georgia and the South Sandwich Islands.

Sovereign states in both hemispheres

Below is a list of the sovereign states which are in both the Western and Eastern Hemispheres on the IERS Reference Meridian, in order from north to south:

IERS Reference Meridian

The IERS Reference Meridian (IRM), also called the International Reference Meridian, is the prime meridian maintained by the International Earth Rotation and Reference Systems Service (IERS). It passes about 5.3 arcseconds east of George Biddell Airy's 1851 transit circle or 102 metres (335 ft) at the latitude of the Royal Observatory, Greenwich. It is also the reference meridian of the Global Positioning System (GPS) operated by the United States Department of Defense, and of WGS84 and its two formal versions, the ideal International Terrestrial Reference System (ITRS) and its realization, the International Terrestrial Reference Frame (ITRF).

Below is a list of the sovereign states which are in both the Western and Eastern Hemispheres along the 180th meridian, in order from north to south. With the exception of the United States (Wake Island), all of them are located on just one side of the International Date Line, which is curved around them.

Countries and territories in the Western Hemisphere but not in the Americas

The following countries and territories lie outside the Americas yet are entirely/mostly or partially within the Western Hemisphere:




Related Research Articles

Longitude A geographic coordinate that specifies the east-west position of a point on the Earths surface

Longitude, is a geographic coordinate that specifies the east–west position of a point on the Earth's surface. 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.

Geographic coordinate system Coordinate system

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.

Southern Hemisphere part of Earth that lies south of the equator

The Southern Hemisphere is the half of Earth that is south of the Equator. It contains all or parts of five continents, four oceans and most of the Pacific Islands in Oceania. Its surface is 80.9% water, compared with 60.7% water in the case of the Northern Hemisphere, and it contains 32.7% of Earth's land.

Time in the United States Timekeeping in the USA

Time in the United States, by law, is divided into nine standard time zones covering the states and its possessions, with most of the United States observing daylight saving time (DST) for approximately the spring, summer, and fall months. The time zone boundaries and DST observance are regulated by the Department of Transportation. Official and highly precise timekeeping services (clocks) are provided by two federal agencies: the National Institute of Standards and Technology (NIST) ; and its military counterpart, the United States Naval Observatory (USNO). The clocks run by these services are kept synchronized with each other as well as with those of other international timekeeping organizations.

Eastern Hemisphere half of the Earth that is east of the prime meridian and west of 180° longitude

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".

Inside Passage water route in northwest North America

The Inside Passage is a coastal route for ships and boats along a network of passages which weave through the islands on the Pacific NW coast of North America. The route extends from southeastern Alaska, in the United States, through western British Columbia, in Canada, to northwestern Washington state, in the United States. Ships using the route can avoid some of the bad weather in the open ocean and may visit some of the many isolated communities along the route. The Inside Passage is heavily travelled by cruise ships, freighters, tugs with tows, fishing craft and ships of the Alaska Marine Highway, BC Ferries, and Washington State Ferries systems.

Shelikof Strait

Shelikof Strait is a strait on the southwestern coast of the U.S. state of Alaska between the Alaska mainland to the west and Kodiak and Afognak islands to the east.

This is a list of the extreme points of The Americas, the points that are farther north, south, east or west than any other location on the continent. The continent's southernmost point is often said to be Cape Horn, which is the southernmost point of the Chilean islands. The Americas cross 134° of longitude east to west and 124° of latitude north to south.

Semisopochnoi Island

Semisopochnoi Island or Unyak Island is part of the Rat Islands group in the western Aleutian Islands of Alaska. The island is uninhabited and provides an important nesting area for maritime birds. The island is of volcanic origin, containing several volcanoes including Mount Cerberus. It has a land area of 85.558 square miles (221.59 km2), measuring 18 kilometres (11 mi) in length and 20 kilometres (12 mi) in width.

Americas (terminology)

The Americas, also known as America, are lands of the western hemisphere, composed of numerous entities and regions variably defined by geography, politics, and culture.

Peirce quincuncial projection map projection

The Peirce quincuncial projection is a conformal map projection developed by Charles Sanders Peirce in 1879. The projection has the distinctive property that it can be tiled ad infinitum on the plane, with edge-crossings being completely smooth except for four singular points per tile. The projection has seen use in digital photography for portraying 360° views. The description quincuncial refers to the arrangement of four quadrants of the globe around the center hemisphere in an overall square pattern. Typically the projection is oriented such that the north pole lies at the center.

Volcanic Seven Summits

The Volcanic Seven Summits are the highest volcanoes on each of the seven continents, just as the Seven Summits are the highest peaks on each of the seven continents. Summiting all seven is regarded as a mountaineering challenge, first postulated as such in 1999.

Boundaries between the continents of Earth

The boundaries between the continents of Earth are generally a matter of geographical convention. Several slightly different conventions are in use. The number of continents is most commonly considered seven but may range as low as four when the Americas and Afro-Eurasia are each considered a single continent. According to the definition of a continent in the strict sense, an island cannot be part of any continent, but by convention and in practice most major islands are associated with a continent.

Nansen Sound

Nansen Sound is an uninhabited strait in Qikiqtaaluk, Nunavut, Canada. It lies between western Grant Land on Ellesmere Island and Axel Heiberg Island. Tanquary Fiord or Greely Fiord enters the sound from the east.

Timbalier Island is an island off southeastern Louisiana in the United States.


  1. 1 2 Olson, Judy M (1997), "Projecting the hemisphere", in Robinson, Arthur H; Snyder, John P, Matching the map projection to the need, Bethesda, MD: Cartography and Geographic Information Society, American Congress on Surveying and Mapping.
    - "Western Hemisphere", Merriam-Webster's Geographical Dictionary (3rd ed.), Springfield, Massachusetts: Merriam-Webster, 2001, p. 1294.
  2. Oxford Dictionary of English (2nd ed.), London, UK: Oxford University Press, 2006, p. 2001
    - "Western /western%20hemisphere", Merriam Webster's Online Dictionary (based on Collegiate vol., 11th ed.), Springfield, MA: Merriam-Webster, 2006
  3. "Western Hemisphere", Britannica.com
  4. "Informe científico que estudia el Aconcagua, el Coloso de América mide 6960,8 metros" [Scientific Report on Aconcagua, the Colossus of America measures 6960,8m] (in Spanish). Universidad Nacional de Cuyo. 2012. Archived from the original on September 8, 2012. Retrieved September 3, 2012.

Coordinates: 0°N90°W / 0°N 90°W / 0; -90