Circle of latitude

A circle of latitude, on the Earth

Earth

Earth is the third planet from the Sun. It is the fifth largest of the eight planets in the solar system, and the largest of the terrestrial planets in the Solar System in terms of diameter, mass and density...

, is an imaginary east

East

East is a direction in geography. It is one of the four cardinal directions or compass points, opposite of west and at right angles to north and south. East is the direction toward which the Earth rotates about its axis, and therefore the general direction from which the Sun appears to rise...

-west

West

West is most commonly a noun, adjective, or adverb indicating direction or geography.West is one of the four cardinal directions or compass points...

 circle connecting all locations (not taking into account elevation) that share a given latitude

Latitude

Latitude, usually denoted by the Greek letter phi gives the location of a place on Earth north or south of the equator. Lines of Latitude are the imaginary horizontal lines shown running east-to-west on maps that run either north or south of the equator...

. A location's position along a circle of latitude is given by its longitude

Longitude

Longitude , identified by the Greek letter lambda , is the geographic coordinate most commonly used in cartography and global navigation for east-west measurement...

.

Circles of latitude are often called parallels because they are parallel to each other. On some map projections, including the Equirectangular projection

Equirectangular projection

The equirectangular projection is a very simple map projection attributed to Marinus of Tyre, who Ptolemy claims invented the projection about 100 AD...

, they are drawn at equidistant intervals.

Circles of latitude become smaller the farther they are from the equator and the closer they are to the poles

Geographical pole

A geographical pole is either of the two points—the north pole and the south pole—on the surface of a rotating planet where the axis of rotation meets the surface of the body...

. A circle of latitude is perpendicular to all meridian

Meridian (geography)

A meridian is an imaginary arc on the Earth's surface from the North Pole to the South Pole that connects all locations running along it with a given longitude. The position of a point on the meridian is given by the latitude. Each meridian is perpendicular to all circles of latitude at the...

s at the points of intersection, and is hence a special case of a loxodrome.

Contrary to what might be assumed from their straight-line representation on some map projections, a circle of latitude is not, with the sole exception of the Equator, the shortest distance between two points lying on the Earth. In other words, circles of latitude (except for the Equator) are not great circle

Great circle

A great circle of a sphere is a circle that runs along the surface of that sphere so as to cut it into two equal halves, as distinct from a small circle. The great circle therefore has both the same circumference and the same center as the sphere...

s, and are not really "lines" in the geometric sense (see also great-circle distance

Great-circle distance

The great-circle distance or orthodromic distance is the shortest distance between any two points on the surface of a sphere measured along a path on the surface of the sphere . Because spherical geometry is rather different from ordinary Euclidean geometry, the equations for distance take on a...

). It is for this reason that an airplane traveling between a European and North American city that share the same latitude will fly farther north, over Greenland

Greenland

Greenland is an autonomous constituent country within the Kingdom of Denmark located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago...

 for example.

Arcs of circles of latitude are sometimes used as boundaries between countries or regions where distinctive natural borders are lacking (such as in deserts), or when an artificial border is drawn as a "line on a map", as happened in Korea

38th parallel north

The 38th parallel north is a circle of latitude that is 38 degrees north of the Earth's equatorial plane. The 38th parallel north has been especially important in the recent history of Korea.-Geography:...

.

Major circles of latitude

There are five major circles of latitude, listed below from north to south:

• Arctic Circle
  Arctic Circle
  The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. In , it is the parallel of latitude that runs approximately 66° 33′ 39″ north of the Equator. The region north of this circle is known as the Arctic, and the zone just to the south is called the Northern...
  
   (66° 33′ 38″ N)
• Tropic of Cancer
  Tropic of Cancer
  The Tropic of Cancer, or the Northern tropic, is one of five major degree measures or major circles of latitude that mark maps of the Earth. It is the northmost latitude at which the sun can appear directly overhead at noon...
  
   (23° 26′ 22″ N)
• Equator
  Equator
  The equator is the intersection of the Earth's surface with the plane perpendicular to the Earth's axis of rotation and containing the Earth's center of mass. In simpler language, it is an imaginary line on the Earth's surface equidistant from the North Pole and South Pole that divides the Earth...
  
   (0° latitude)
• Tropic of Capricorn
  Tropic of Capricorn
  The Tropic of Capricorn, or Southern tropic, is one of the five major circles of latitude that mark maps of the Earth. It lies 23° 26′ 22″ south of the equator, and marks the most southerly latitude at which the sun can appear directly overhead at noon...
  
   (23° 26′ 22″ S)
• Antarctic Circle
  Antarctic Circle
  The Antarctic Circle is one of the five major circles of latitude that mark maps of the Earth. As of , it lies at latitude 66° 33′ 39″ south of the equator. The area south of the Antarctic Circle is known as the Antarctic, and the zone immediately to the north is called the Southern Temperate Zone...
  
   (66° 33′ 38″ S)

These circles of latitude (excluding the equator) mark the divisions between the five principal geographical zone

Geographical zone

Each of the five main latitude regions of the earth's surface is said to be a geographical zone, divided by the major circles of latitude. The differences between them relate to climate, and the behaviour of the sun...

s.

Equator

The equator is the circle that is equidistant from both the North Pole

North Pole

The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets the Earth's surface...

 and South Pole

South Pole

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

.
It divides the Earth into the Northern Hemisphere

Northern Hemisphere

The Northern Hemisphere is the half of a planet that is north of the equator—the word hemisphere literally means 'half sphere'. It is also that half of the celestial sphere north of the celestial equator...

 and the Southern Hemisphere

Southern Hemisphere

The Southern Hemisphere is the half of a planet that is south of the equator—the word hemisphere literally means 'half ball'...

.

Equator Equator The equator is the intersection of the Earth's surface with the plane perpendicular to the Earth's axis of rotation and containing the Earth's center of mass. In simpler language, it is an imaginary line on the Earth's surface equidistant from the North Pole and South Pole that divides the Earth...

Arctic and Antarctic Circles

The Arctic Circle marks the southernmost latitude (in the Northern Hemisphere

Northern Hemisphere

The Northern Hemisphere is the half of a planet that is north of the equator—the word hemisphere literally means 'half sphere'. It is also that half of the celestial sphere north of the celestial equator...

) at which the sun can remain continuously above or below the horizon for 24 hours. Similarly, the Antarctic Circle marks the northernmost latitude (in the Southern Hemisphere

Southern Hemisphere

The Southern Hemisphere is the half of a planet that is south of the equator—the word hemisphere literally means 'half ball'...

) at which the sun can remain continuously above or below the horizon for 24 hours.

The latitude of these circles plus the Earth's axial tilt

Axial tilt

In astronomy, axial tilt is the angle between an object's rotational axis and a line perpendicular to its orbital plane. The angle is measured between the line perpendicular to object's orbital plane and object's rotational axis passing through north pole at which the planet appears to rotate...

 is equal to 90°.

Arctic Circle Arctic Circle The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. In , it is the parallel of latitude that runs approximately 66° 33′ 39″ north of the Equator. The region north of this circle is known as the Arctic, and the zone just to the south is called the Northern...

Antarctic Circle Antarctic Circle The Antarctic Circle is one of the five major circles of latitude that mark maps of the Earth. As of , it lies at latitude 66° 33′ 39″ south of the equator. The area south of the Antarctic Circle is known as the Antarctic, and the zone immediately to the north is called the Southern Temperate Zone...

Tropics of Cancer and Capricorn

The Tropic of Cancer and Tropic of Capricorn respectively mark the northernmost and southernmost latitudes at which the sun may be seen directly overhead (at the June solstice and December solstice respectively).

The latitude of the tropic circles is equal to the Earth's axial tilt

Axial tilt

In astronomy, axial tilt is the angle between an object's rotational axis and a line perpendicular to its orbital plane. The angle is measured between the line perpendicular to object's orbital plane and object's rotational axis passing through north pole at which the planet appears to rotate...

.

Tropic of Cancer Tropic of Cancer The Tropic of Cancer, or the Northern tropic, is one of five major degree measures or major circles of latitude that mark maps of the Earth. It is the northmost latitude at which the sun can appear directly overhead at noon...

Tropic of Capricorn Tropic of Capricorn The Tropic of Capricorn, or Southern tropic, is one of the five major circles of latitude that mark maps of the Earth. It lies 23° 26′ 22″ south of the equator, and marks the most southerly latitude at which the sun can appear directly overhead at noon...

Movement of the Tropics and the Arctic and Antarctic circles

See also: Axial tilt

Axial tilt

In astronomy, axial tilt is the angle between an object's rotational axis and a line perpendicular to its orbital plane. The angle is measured between the line perpendicular to object's orbital plane and object's rotational axis passing through north pole at which the planet appears to rotate...

.

By definition, the positions of the Tropic of Cancer

Tropic of Cancer

The Tropic of Cancer, or the Northern tropic, is one of five major degree measures or major circles of latitude that mark maps of the Earth. It is the northmost latitude at which the sun can appear directly overhead at noon...

, Tropic of Capricorn

Tropic of Capricorn

The Tropic of Capricorn, or Southern tropic, is one of the five major circles of latitude that mark maps of the Earth. It lies 23° 26′ 22″ south of the equator, and marks the most southerly latitude at which the sun can appear directly overhead at noon...

, Arctic Circle

Arctic Circle

The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. In , it is the parallel of latitude that runs approximately 66° 33′ 39″ north of the Equator. The region north of this circle is known as the Arctic, and the zone just to the south is called the Northern...

 and Antarctic Circle

Antarctic Circle

The Antarctic Circle is one of the five major circles of latitude that mark maps of the Earth. As of , it lies at latitude 66° 33′ 39″ south of the equator. The area south of the Antarctic Circle is known as the Antarctic, and the zone immediately to the north is called the Southern Temperate Zone...

 all depend on the tilt of the Earth's axis

Axial tilt

In astronomy, axial tilt is the angle between an object's rotational axis and a line perpendicular to its orbital plane. The angle is measured between the line perpendicular to object's orbital plane and object's rotational axis passing through north pole at which the planet appears to rotate...

 relative to the plane of its orbit around the sun, known technically as the "obliquity of the ecliptic". As of 2000, the mean value of the tilt was about 23° 26′ 21″. However, this angle is not constant, but has a complex motion determined by the superimposition of many different cycles with short to very long periods. As the axial tilt varies, so do the positions of the Tropics and the Arctic and Antarctic circles.

The main long-term cycle causes the axial tilt to fluctuate between about 22.1° and 24.5° with a 41,000 year periodicity. As a consequence of this cycle the average value of the tilt is currently decreasing by about 0.47″ per year. This causes the Tropics of Cancer and Capricorn to drift towards the equator by about 15 metres per year, and the Arctic and Antarctic Circles to drift towards the Poles by the same amount. As a result of the movement of the Tropics of Cancer and Capricorn, the area of the Tropics

Tropics

The tropics,the tropics are very hot. hi everyone! peace out!seated in the equatorial regions of the world, are limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately 23°26' N latitude and the Tropic of Capricorn in the southern hemisphere at 23°26' S latitude...

 decreases worldwide by about 1100 square kilometres per year on average.

The Earth's axial tilt is subject to additional shorter-term variations due to nutation

Nutation

Nutation is a slight irregular motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight...

, of which the main term, with a period of 18.7 years, has an amplitude

Amplitude

Amplitude is the magnitude of change in the oscillating variable, with each oscillation, within an oscillating system. For instance, sound waves are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...

 of 9" 21 (corresponding to almost 300 metres north and south). There are then still many smaller terms, resulting in varying daily shifts of some metres in any direction.

Finally, the Earth's rotational axis is not exactly fixed with respect to the Earth, but undergoes very small fluctuations, called polar motion

Polar motion

Polar motion is the movement of Earth's rotation axis across its surface. This is measured with respect to a reference frame in which the solid Earth is fixed...

, which have a small theoretical effect on the positions of the abovementioned parallels.

Short-term fluctuations over a matter of days do not directly affect the location of the extreme latitudes at which the sun may appear directly overhead, or at which 24-hour day or night is possible, except when they actually occur at the time of the solstices. Rather, they cause a theoretical shifting of the parallels, that would occur if the given axis tilt were maintained throughout the year.

Other notable parallels

A number of sub-national and international border

Border

Borders define geographic boundaries of political entities or legal jurisdictions, such as governments, states or subnational administrative divisions. They may foster the setting up of buffer zones...

s are defined by parallels.

Parallel	Description
70°N 70th parallel north The 70th parallel north is a circle of latitude that is 70 degrees north of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 70° north passes through:-See also:*69th parallel north*71st parallel north...	On Victoria Island, , two sections of the border between Northwest Territories Northwest Territories The Northwest Territories is a federal territory of Canada....  and Nunavut Nunavut Nunavut is the largest and newest federal territory of Canada; it was separated officially from the Northwest Territories on April 1, 1999 via the Nunavut Act and the Nunavut Land Claims Agreement Act, though the actual boundaries had been established in 1993... .
60°N 60th parallel north The 60th parallel north is a circle of latitude that is 60 degrees north of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 60° north passes through:-Canada:...	In , the southern border of Yukon Yukon Yukon , or The Yukon, is the westernmost and smallest of Canada's three federal territories. It was named after the Yukon River, Yukon meaning "Great River" in Gwich’in....  with the northern border of British Columbia British Columbia British Columbia is the westernmost of Canada's provinces and is famed for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . In 1871, it became the sixth province of Canada.The capital of British Columbia is Victoria, the 15th largest metropolitan region in Canada... ; the southern border of Northwest Territories Northwest Territories The Northwest Territories is a federal territory of Canada....  with the northern borders of British Columbia British Columbia British Columbia is the westernmost of Canada's provinces and is famed for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . In 1871, it became the sixth province of Canada.The capital of British Columbia is Victoria, the 15th largest metropolitan region in Canada... , Alberta Alberta Alberta is one of Canada's prairie provinces. It became a province on September 1, 1905.Alberta is located in western Canada, bounded by the provinces of British Columbia to the west and Saskatchewan to the east, the Northwest Territories to the north, and the U.S. state of Montana to the south....  and Saskatchewan Saskatchewan Saskatchewan is a prairie province in Canada, which has an area of and a population of 1,023,810 , mostly living in the southern half of the province. Of these, 233,923 live in the province's largest city, Saskatoon, while 194,971 live in the provincial capital, Regina... ; and the southern border of mainland Nunavut Nunavut Nunavut is the largest and newest federal territory of Canada; it was separated officially from the Northwest Territories on April 1, 1999 via the Nunavut Act and the Nunavut Land Claims Agreement Act, though the actual boundaries had been established in 1993...  with the northern border of Manitoba Manitoba Manitoba is a prairie province in Canada and has an area of . Manitoba is bordered by the provinces of Ontario to the east and Saskatchewan to the west, the territory of Nunavut to the north, and the U.S. states of North Dakota and Minnesota to the south... ).
54°40'N	The border between 19th century Russian and British land claims in western North America which played a role in the Oregon boundary dispute Oregon boundary dispute The Oregon boundary dispute, or the Oregon Question, arose as a result of competing British and American claims to the Pacific Northwest of North America in the first half of the 19th century. Both the United Kingdom and the United States had territorial and commercial aspirations in the region...  between Britain and the United States, giving rise to the slogan "Fifty-four forty or fight."
52°N 52nd parallel north The 52nd parallel north is a circle of latitude that is 52 degrees north of the Earth's equatorial plane.In Canada, part of the border between Quebec and Newfoundland and Labrador is defined by the parallel....	In , part of the border between Newfoundland and Labrador Newfoundland and Labrador Newfoundland and Labrador is a province of Canada on the country's Atlantic coast in northeastern North America. This easternmost Canadian province comprises two main parts: the island of Newfoundland off the country's eastern coast, and Labrador on the mainland to the northwest of the island.A...  and Quebec Quebec Quebec is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking identity and the only one whose sole official language is French at the provincial level.... .
49°N 49th parallel north The 49th parallel north is a circle of latitude that is 49 degrees north of the Earth's equatorial plane.The parallel forms part of the United States-Canadian Border from British Columbia to Manitoba on the Canadian side and from Washington to Minnesota on the U.S. side, or from the Strait of...	Much of the border between and the , from Washington Washington Washington is a state in the Pacific Northwest region of the United States. Washington was carved out of the western part of Washington Territory which had been ceded by Britain in 1846 by the Oregon Treaty as settlement of the Oregon Boundary Dispute. It was admitted to the Union as the...  to western Minnesota Minnesota Minnesota is a state in the Midwestern region of the United States. The twelfth largest state by area in the U.S., it is the twenty-first most populous, with 5.2 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the... .
48°N 48th parallel north The 48th parallel north is a circle of latitude that is 48 degrees north of the Earth's equatorial plane.- Geography :Starting at the Prime Meridian and heading eastwards, the parallel 48° north passes through:-See also:*47th parallel north...	In , part of the border between Quebec Quebec Quebec is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking identity and the only one whose sole official language is French at the provincial level....  and New Brunswick New Brunswick New Brunswick is one of Canada's three Maritime provinces and is the only constitutionally bilingual province in the confederation. The provincial capital is Fredericton... .
45°N	The theoretical halfway point between the Equator and the North Pole. Part of the border between (Quebec Quebec Quebec is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking identity and the only one whose sole official language is French at the provincial level.... ) and the (New York New York New York is a state in the Mid-Atlantic and Northeastern regions of the United States and is the nation's third most populous. The state is bordered by New Jersey and Pennsylvania to the south, and Connecticut, Massachusetts and Vermont to the east...  and Vermont Vermont The State of Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd by land area, , and 45th by total area. It has a population of 621,270, making it the second least-populated state... ). Also, in the , most of the border between Montana Montana Montana is a state in the Western United States. The western third of the state contains numerous mountain ranges; other 'island' ranges are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...  and Wyoming Wyoming Wyoming is a state in the Western United States. The majority of the state is dominated by the mountain ranges and rangelands of the Rocky Mountain West, while the easternmost section of the state includes part of a high elevation prairie region known as the High Plains. While the tenth largest... .
43°N 43rd parallel north The 43rd parallel north is a circle of latitude that is 43 degrees north of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 43° north passes through:-United States:...	In the , much of the border between South Dakota South Dakota South Dakota is a state located in the Midwestern region of the United States of America. It is named after the Lakota and Dakota Sioux American Indian tribes. South Dakota was carved out of the southern half of the Dakota Territory and admitted to the Union on November 2, 1889...  and Nebraska Nebraska Nebraska is a state located on the Great Plains of the Midwestern United States. The state's capital is Lincoln and its largest city is Omaha.... .
42°N 42nd parallel north The 42nd parallel north is a circle of latitude that is 42 degrees north of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 42° north passes through:-United States:...	In the , the southern borders of Oregon Oregon Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...  and Idaho Idaho Idaho is a state in the Pacific Northwest region of the United States of America. The state's largest city and capital is Boise. Residents are called "Idahoans." Idaho was admitted to the Union on 3 July 1890 as the 43rd state....  where they meet the northern borders of California California California is the most populous state in the United States, and the third largest by area. California is the second most populous sub-national entity in the Americas, behind only São Paulo, Brazil... , Nevada Nevada Nevada is a state located in the western region of the United States. The capital is Carson City and the largest city is Las Vegas. The state's nickname is Silver State, due to the large number of silver deposits that were discovered and mined there...  and Utah Utah Utah is a western state of the United States. It was the 45th state admitted to the Union, on January 4, 1896. Approximately 80 percent of Utah's 2,736,424 people live along the Wasatch Front, centering around Salt Lake City. In contrast, vast expanses of the state are nearly uninhabited, making... . The parallel also defines much of the border between Pennsylvania Pennsylvania The Commonwealth of Pennsylvania , often colloquially referred to as PA by natives and Northeasterners, is a state located in the Northeastern and Middle Atlantic regions of the United States...  and New York New York New York is a state in the Mid-Atlantic and Northeastern regions of the United States and is the nation's third most populous. The state is bordered by New Jersey and Pennsylvania to the south, and Connecticut, Massachusetts and Vermont to the east... .
41°N 41st parallel north The 41st parallel north is a circle of latitude that is 41 degrees north of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 41° north passes through:-United States:...	In the , part of the border between Wyoming Wyoming Wyoming is a state in the Western United States. The majority of the state is dominated by the mountain ranges and rangelands of the Rocky Mountain West, while the easternmost section of the state includes part of a high elevation prairie region known as the High Plains. While the tenth largest...  and Utah Utah Utah is a western state of the United States. It was the 45th state admitted to the Union, on January 4, 1896. Approximately 80 percent of Utah's 2,736,424 people live along the Wasatch Front, centering around Salt Lake City. In contrast, vast expanses of the state are nearly uninhabited, making... , the border between Wyoming Wyoming Wyoming is a state in the Western United States. The majority of the state is dominated by the mountain ranges and rangelands of the Rocky Mountain West, while the easternmost section of the state includes part of a high elevation prairie region known as the High Plains. While the tenth largest...  and Colorado Colorado Colorado is a U.S. state located in the Rocky Mountain region of the United States of America. It may also be considered to be part of the Western and Southwestern regions of the United States. Colorado entered statehood in 1876 and was nicknamed the “Centennial State”... , and part of the border between Nebraska Nebraska Nebraska is a state located on the Great Plains of the Midwestern United States. The state's capital is Lincoln and its largest city is Omaha....  and Colorado Colorado Colorado is a U.S. state located in the Rocky Mountain region of the United States of America. It may also be considered to be part of the Western and Southwestern regions of the United States. Colorado entered statehood in 1876 and was nicknamed the “Centennial State”... .
40°N 40th parallel north The 40th parallel north is a circle of latitude that is 40 degrees north of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 40° north passes through:-United States:...	In the , the border between Nebraska Nebraska Nebraska is a state located on the Great Plains of the Midwestern United States. The state's capital is Lincoln and its largest city is Omaha....  and Kansas Kansas Kansas is a state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa tribe, who inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south wind," although this was... . The parallel was originally chosen for the Mason-Dixon Line Mason-Dixon line The Mason-Dixon Line was surveyed between 1763 and 1767 by Charles Mason and Jeremiah Dixon in the resolution of a border dispute between British colonies in Colonial America. It forms a demarcation line among four U.S. states, forming part of the borders of Pennsylvania, Maryland, Delaware, and... , but the line was moved several miles south to avoid bisecting the city of Philadelphia.
38°N 38th parallel north The 38th parallel north is a circle of latitude that is 38 degrees north of the Earth's equatorial plane. The 38th parallel north has been especially important in the recent history of Korea.-Geography:...	The boundary between the Soviet Soviet Union The Union of Soviet Socialist Republics was a constitutionally socialist state that existed in Eurasia from 1922 to 1991. The name is a translation of the , tr. Soyuz Sovetskikh Sotsialisticheskikh Respublik, abbreviated СССР, SSSR. The common short name is Soviet Union, from , Sovetskiy Soyuz...  and American occupation zones in Korea Korea Korea is a civilization and formerly unified nation currently divided into two states. Located on the Korean Peninsula, it borders China to the northwest, Russia to the northeast, and is separated from Japan to the east by the Korea Strait....  from 1945 until Korean War Korean War The Korean War is a war that started between North Korea and South Korea on 25 June 1950 and paused with an armistice signed 27 July, 1953...  (1950-1953).
37°N 37th parallel north The 37th parallel north is a circle of latitude that is 37 degrees north of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 37° north passes through:-United States:...	In the , the southern border of Utah Utah Utah is a western state of the United States. It was the 45th state admitted to the Union, on January 4, 1896. Approximately 80 percent of Utah's 2,736,424 people live along the Wasatch Front, centering around Salt Lake City. In contrast, vast expanses of the state are nearly uninhabited, making...  with the northern border of Arizona Arizona The State of Arizona is a state located in the southwestern region of the United States. The capital and largest city is Phoenix. The second largest city is Tucson, followed in size by the four Phoenix metropolitan area cities of Mesa, Glendale, Chandler, and Scottsdale.Arizona was the 48th and... . The southern border of Colorado Colorado Colorado is a U.S. state located in the Rocky Mountain region of the United States of America. It may also be considered to be part of the Western and Southwestern regions of the United States. Colorado entered statehood in 1876 and was nicknamed the “Centennial State”...  with the northern borders of New Mexico New Mexico New Mexico is a state located in the southwestern region of the United States. Inhabited by Native American populations for many centuries, it has also been part of the Imperial Spanish viceroyalty of New Spain, part of Mexico, and a U.S. territory. Among U.S...  and Oklahoma Oklahoma Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,617,316 residents in 2007 and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state... . The southern border of Kansas Kansas Kansas is a state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa tribe, who inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south wind," although this was...  with the northern border of Oklahoma Oklahoma Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,617,316 residents in 2007 and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state... .
36°30'N	The historic Missouri Compromise Missouri Compromise The Missouri Compromise was an agreement passed in 1820 between the pro-slavery and anti-slavery factions in the United States Congress, involving primarily the regulation of slavery in the western territories. It prohibited slavery in the former Louisiana Territory north of the parallel 36°30'...  line. In the , defines part of the border between Oklahoma Oklahoma Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,617,316 residents in 2007 and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...  and Texas Texas Texas is the second-largest U.S. state in both area and population, and the largest state in the contiguous United States.The name had wide usage among native Americans, meaning "friends" or "allies"... , most of the border between Missouri Missouri Missouri is a state in the Midwest region of the United States bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. Missouri is the 18th most populous state with a 2008 estimated population of 5,911,605. It comprises 114 counties and one independent city....  and Arkansas Arkansas Arkansas is a state located in the southern region of the United States. Its name is an Algonquin name of the Quapaw Indians. Arkansas shares a border with six states, with its eastern border largely defined by the Mississippi River. Its diverse geography ranges from the mountainous regions of the... . Geographically it is a Westward extension of the border between Virginia Virginia The Commonwealth of Virginia is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" because it is the birthplace of eight U.S. presidents. The geography and climate of the state are shaped by the Blue...  and North Carolina North Carolina North Carolina is a state located on the Atlantic Seaboard in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties...  and part of the border between Kentucky Kentucky The Commonwealth of Kentucky is a state located in the East Central United States of America. Kentucky is a Southern state situated in the Upland South, although the state is infrequently placed, geographically and culturally, in the Midwest. Kentucky is one of four U.S. states constituted as a...  and Tennessee Tennessee Tennessee is a state located in the Southeastern United States. According to the 2008 census, it has a population of 6,214,888, an increase of nearly 9.5% since 2000. Tennessee is the 14th fastest growing state in the US and is ranked 17th by population. It is ranked 36th by total land area. In... .
36°N 36th parallel north The 36th parallel north is a circle of latitude that is 36 degrees north of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 36° north passes through:-United States:...	In the , a short section of the border between the Missouri Bootheel and Arkansas Arkansas Arkansas is a state located in the southern region of the United States. Its name is an Algonquin name of the Quapaw Indians. Arkansas shares a border with six states, with its eastern border largely defined by the Mississippi River. Its diverse geography ranges from the mountainous regions of the... .
35°N 35th parallel north The 35th parallel north is a circle of latitude that is 35 degrees north of the Earth's equatorial plane.In the United States, the parallel defines the southern border of Tennessee, and the border between North Carolina and Georgia....	In the , the southern border of Tennessee Tennessee Tennessee is a state located in the Southeastern United States. According to the 2008 census, it has a population of 6,214,888, an increase of nearly 9.5% since 2000. Tennessee is the 14th fastest growing state in the US and is ranked 17th by population. It is ranked 36th by total land area. In... , which meets Mississippi Mississippi Mississippi is a state located in the Southern United States. Jackson is the state capital and largest city. The state's name comes from the Mississippi River, which flows along its western boundary, and takes its name from the Ojibwe word misi-ziibi . The state is heavily forested outside of the... , Alabama Alabama Alabama is a state located in the southeastern region of the United States of America. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its...  and Georgia Georgia (U.S. state) Georgia is a state in the United States. One of the original Thirteen Colonies that revolted against British rule in the American Revolution, it had been the last of the Thirteen Colonies to be established, in 1733. Georgia was the fourth state to ratify the United States Constitution, on January... . Also, part of the border between North Carolina North Carolina North Carolina is a state located on the Atlantic Seaboard in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties...  and Georgia Georgia (U.S. state) Georgia is a state in the United States. One of the original Thirteen Colonies that revolted against British rule in the American Revolution, it had been the last of the Thirteen Colonies to be established, in 1733. Georgia was the fourth state to ratify the United States Constitution, on January... .
33°N 33rd parallel north The 33rd parallel north is a circle of latitude that is 33 degrees north of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 33° north passes through:...	In the , the southern border of Arkansas Arkansas Arkansas is a state located in the southern region of the United States. Its name is an Algonquin name of the Quapaw Indians. Arkansas shares a border with six states, with its eastern border largely defined by the Mississippi River. Its diverse geography ranges from the mountainous regions of the... , which meets the northern border of Louisiana Louisiana The State of Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state divided into parishes, which are local governments equivalent to counties... . Historically, it defined the southern border of the Louisiana Territory Louisiana Territory The Territory of Louisiana was an organized incorporated territory of the United States that existed from July 4, 1805, until June 4, 1812, when it was renamed the Territory of Missouri.... .
32°N 32nd parallel north The 32nd parallel north is a circle of latitude that is 32 degrees north of the Earth's equatorial plane.In the United States, the parallel defines part of the border between New Mexico and Texas....	In the , part of the border between New Mexico New Mexico New Mexico is a state located in the southwestern region of the United States. Inhabited by Native American populations for many centuries, it has also been part of the Imperial Spanish viceroyalty of New Spain, part of Mexico, and a U.S. territory. Among U.S...  and Texas Texas Texas is the second-largest U.S. state in both area and population, and the largest state in the contiguous United States.The name had wide usage among native Americans, meaning "friends" or "allies"... .
31°N 31st parallel north The 31st parallel north is a circle of latitude that is 31 degrees north of the Earth's equatorial plane.Part of the border between Iran and Iraq is defined by the parallel....	Part of the border between and . In the , part of the border between Mississippi Mississippi Mississippi is a state located in the Southern United States. Jackson is the state capital and largest city. The state's name comes from the Mississippi River, which flows along its western boundary, and takes its name from the Ojibwe word misi-ziibi . The state is heavily forested outside of the...  and Louisiana Louisiana The State of Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state divided into parishes, which are local governments equivalent to counties... , and part of the border between Alabama Alabama Alabama is a state located in the southeastern region of the United States of America. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its...  and Florida Florida Florida is a state located in the southeastern region of the United States, bordering Alabama to the northwest and Georgia to the north. It was the 27th state admitted to the United States... .
28°N 28th parallel north The 28th parallel north is a circle of latitude that is 28 degrees north of the Earth's equatorial plane. It crosses Africa, Asia, the Pacific Ocean, North America and the Atlantic Ocean....	In , the border between Baja California Baja California Baja California is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises the northern half of the Baja California peninsula, north...  and Baja California Sur Baja California Sur Baja California Sur is one of the 31 states of Mexico. Before becoming a state in 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises the southern half of the Baja California peninsula, south of the 28th parallel... .
26°N 26th parallel north The 26th parallel north is a circle of latitude that is 26 degrees north of the Earth's equatorial plane. It crosses Africa, Asia, the Indian Ocean, the Pacific Ocean, North America and the Atlantic Ocean....	Part of the border between Western Sahara Western Sahara Western Sahara is a territory of North Africa, bordered by Morocco to the north, Algeria to the northeast, Mauritania to the east and south, and the Atlantic Ocean to the west. Its surface area amounts to . It is one of the most sparsely populated territories in the world, mainly consisting of...  (claimed by ) and .
25°N 25th parallel north The 25th parallel north is a circle of latitude that is 25 degrees north of the Earth's equatorial plane. It crosses Africa, Asia, the Indian Ocean, the Pacific Ocean, North America and the Atlantic Ocean....	Part of the border between and .
24°N 24th parallel north The 24th parallel north is a circle of latitude that is 24 degrees north of the Earth's equatorial plane. It crosses Africa, Asia, the Indian Ocean, the Pacific Ocean, North America and the Atlantic Ocean....	A short section of the border between and (Burma).
22°N 22nd parallel north The 22nd parallel north is a circle of latitude that is 22 degrees north of the Earth's equatorial plane. It crosses Africa, Asia, the Indian Ocean, the Pacific Ocean, North America, the Caribbean and the Atlantic Ocean....	Much of the border between and , partly disputed (see also Hala'ib Triangle Hala'ib Triangle The Halayeb Triangle or Hala'ib Triangle is an area of land measuring 20,580 km² located on the Red Sea's African coast, between the political borders of Egypt and the administrative boundary... ).
20°N 20th parallel north The 20th parallel north is a circle of latitude that is 20 degrees north of the Earth's equatorial plane. It crosses Africa, Asia, the Indian Ocean, the Pacific Ocean, North America, the Caribbean and the Atlantic Ocean....	A short section of the border between and , and within Sudan, the northern border of the Darfur Darfur Darfur is a region in Sudan. An independent sultanate for several hundred years, it was incorporated into Sudan by Anglo-Egyptian forces. The region is divided into three federal states: West Darfur, South Darfur, and North Darfur which are coordinated by a Transitional Darfur Regional Authority...  region.
17°N 17th parallel north The 17th parallel north is a circle of latitude that is 17 degrees north of the Earth's equatorial plane. It crosses Africa, Asia, the Indian Ocean, the Pacific Ocean, Central America, the Caribbean and the Atlantic Ocean....	The division between Republic of Vietnam (South Vietnam) and Democratic Republic of Vietnam (North Vietnam) during the Vietnam War Vietnam War The Vietnam War or the Second Indochina War was a Cold War military conflict that occurred in Vietnam, Laos, and Cambodia from 1959 to 30 April 1975... .
10°N 10th parallel north The 10th parallel north is a circle of latitude that is 10 degrees north of the Earth's equatorial plane. It crosses Africa, the Indian Ocean, South Asia, Southeast Asia, the Pacific Ocean, Central America, South America and the Atlantic Ocean....	Part of the border between and .
8°N 8th parallel north The 8th parallel north is a circle of latitude that is 8 degrees north of the Earth's equatorial plane. It crosses Africa, the Indian Ocean, South Asia, Southeast Asia, the Pacific Ocean, Central America, South America and the Atlantic Ocean....	Part of the border between and .
1°N 1st parallel north The 1st parallel north is a circle of latitude that is 1 degree north of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Southeast Asia, the Pacific Ocean and South America....	Part of the border between and .
1°S 1st parallel south The 1st parallel south is a circle of latitude that is 1 degree south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Southeast Asia, Australasia, the Pacific Ocean and South America....	Most of the border between and , and a very short section of the border between and in Lake Victoria Lake Victoria Lake Victoria or Victoria Nyanza is one of the African Great Lakes. The lake was named after the United Kingdom's Queen Victoria, by John Hanning Speke, the first European to see the lake.... .
7°S 7th parallel south The 7th parallel south is a circle of latitude that is 7 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Southeast Asia, Australasia, the Pacific Ocean and South America....	A short section of the border between and .
8°S 8th parallel south The 8th parallel south is a circle of latitude that is 8 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Southeast Asia, Australasia, the Pacific Ocean and South America....	Two short sections of the border between and .
10°S 10th parallel south The 10th parallel south is a circle of latitude that is 10 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America....	A short section of the border between and .
13°S 13th parallel south The 13th parallel south is a circle of latitude that is 13 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America....	Part of the border between and .
13°S 13th parallel south The 13th parallel south is a circle of latitude that is 13 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America....	Part of the border between and .
16°S 16th parallel south The 16th parallel south is a circle of latitude that is 16 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America....	Part of the border between and .
22°S 22nd parallel south The 22nd parallel south is a circle of latitude that is 22 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America....	A short section of the border between and , and parts of the border between and .
26°S 26th parallel south The 26th parallel south is a circle of latitude that is 26 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America....	In , the border between South Australia South Australia South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories....  and the Northern Territory Northern Territory The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions... , and part of the border between South Australia South Australia South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories....  and Queensland Queensland Queensland is a state of Australia that occupies the north-eastern section of the mainland continent. It is bordered by the Northern Territory to the west, South Australia to the south-west and New South Wales to the south. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean... .
29°S 29th parallel south The 29th parallel south is a circle of latitude that is 29 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America....	In , much of the border between Queensland Queensland Queensland is a state of Australia that occupies the north-eastern section of the mainland continent. It is bordered by the Northern Territory to the west, South Australia to the south-west and New South Wales to the south. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...  and New South Wales New South Wales New South Wales is Australia's most populous state, located in the south-east of the country, north of Victoria, south of Queensland and east of South Australia... .
35°S 35th parallel south The 35th parallel south is a circle of latitude that is 35 degrees south of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 35° south passes through:-See also:*34th parallel south*36th parallel south...	In , part of the border between Córdoba Province Córdoba Province (Argentina) Córdoba is a province of Argentina, located in the center of the country. Its capital, Córdoba, is the second largest city in the country.Neighboring provinces are : Santiago del Estero, Santa Fe, Buenos Aires, La Pampa, San Luis, La Rioja and Catamarca.Together with Santa Fe and Entre Ríos, the...  and La Pampa Province La Pampa Province La Pampa is a sparsely populated province of Argentina, located in the Pampas in the center of the country. Neighboring provinces are from the north clockwise San Luis, Córdoba, Buenos Aires, Río Negro, Neuquén and Mendoza.-History:... .
36°S 36th parallel south The 36th parallel south is a circle of latitude that is 36 degrees south of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 36° south passes through:- See also :*35th parallel south*37th parallel south...	In , part of the border between Mendoza Province Mendoza Province Mendoza is one of the 23 provinces of Argentina, located in the western central part of the country in the Cuyo region. Neighboring provinces are from the north clockwise San Juan, San Luis, La Pampa, and Neuquén. To the west is Chile.-History:...  and La Pampa Province La Pampa Province La Pampa is a sparsely populated province of Argentina, located in the Pampas in the center of the country. Neighboring provinces are from the north clockwise San Luis, Córdoba, Buenos Aires, Río Negro, Neuquén and Mendoza.-History:... .
42°S 42nd parallel south The 42nd parallel south is a circle of latitude that is 42 degrees south of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 42° south passes through:-See also:*41st parallel south*43rd parallel south...	In , the border between Río Negro Province Río Negro Province Río Negro is a province of Argentina, located at the northern edge of Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean.Its capital is Viedma...  and Chubut Province Chubut Province Chubut a province in the southern part of Argentina situated between the 42nd Parallel South and 46th Parallel South , the Andes range separating Argentina from Chile, and the Atlantic ocean... .
45°S 45th parallel south The 45th parallel south is a circle of latitude that is 45 degrees south of the Earth's equatorial plane. The parallel is the line that marks the theoretical halfway point between the equator and the South Pole...	The theoretical halfway point between the Equator and the South Pole.
46°S 46th parallel south The 46th parallel south is a circle of latitude that is 46 degrees south of the Earth's equatorial plane.Starting at the Prime Meridian and heading eastwards, the parallel 46° south passes through:-See also:*45th parallel south*47th parallel south...	In , the border between Chubut Province Chubut Province Chubut a province in the southern part of Argentina situated between the 42nd Parallel South and 46th Parallel South , the Andes range separating Argentina from Chile, and the Atlantic ocean...  and Santa Cruz Province Santa Cruz Province (Argentina) Santa Cruz is a province of Argentina, located in the southern part of the country, in Patagonia. It borders Chubut province to the north, and Chile to the west and south. To the east is the Atlantic Ocean... .
52°S 52nd parallel south The 52nd parallel south is a circle of latitude that is 52 degrees south of the Earth's equatorial plane.The parallel defines part of the border between Argentina and Chile....	Part of the border between and .
60°S 60th parallel south The 60th parallel south is a circle of latitude that is 60 degrees south of the Earth's equatorial plane. The latitudes below this parallel are often referred to as the Screaming 60's due to the prevailing, high-speed, westerly winds which can generate large waves in excess of 50 feet and peak wind...	The northern boundary of for the purposes of the Antarctic Treaty System Antarctic Treaty System The Antarctic Treaty and related agreements, collectively called the Antarctic Treaty System or ATS, regulate international relations with respect to Antarctica, Earth's only continent without a native human population. For the purposes of the treaty system, Antarctica is defined as all land and...  (see map). The northern boundary of the Southern Ocean Southern Ocean The Southern Ocean, also known as the Great Southern Ocean, the Antarctic Ocean and the South Polar Ocean, comprises the southernmost waters of the World Ocean south of 60° S latitude. The International Hydrographic Organization has designated the Southern Ocean as an oceanic division encircling... .

Altitude

Altitude has an effect on a location's position relative to the plane

Plane (mathematics)

In mathematics, a plane is a flat surface. Planes can arise as subspaces of some higher dimensional space, as with the walls of a room, or they may enjoy an independent existence in their own right, as in the setting of Euclidean geometry....

 formed by a circle of latitude. Since latitude is determined by the normal

Surface normal

A surface normal, or simply normal, to a flat surface is a vector which is perpendicular to that surface. A normal to a non-flat surface at a point P on the surface is a vector perpendicular to the tangent plane to that surface at P. The word "normal" is also used as an adjective: a line normal to...

 to the Earth's surface, locations sharing the same latitude—but having different elevations (e.g., lying along this normal)—no longer lie within this plane. Rather, all points sharing the same latitude and of varying elevation occupy a cone

Conical surface

In geometry, a conical surface is the unbounded surface formed by the union of all the straight lines that pass through a fixed point — the apex or vertex — and any point of some fixed space curve — the directrix — that does not contain the apex...

formed by the rotation of this normal around the Earth's axis.

See also

• U.S. Naval Observatory - mean obliquity of the ecliptic
• Muslim pray time calculations