Antarctic Circle
Encyclopedia
The Antarctic Circle is one of the five major circles (or parallels) of latitude
that mark maps of the Earth
. For 2011, it is the parallel of latitude
that runs south of the Equator
.
, and the zone immediately to the north is called the Southern Temperate Zone
. The equivalent line of latitude in the northern hemisphere is the Arctic Circle
.
Every place south of the Antarctic Circle experiences a period of twenty-four hours' continuous daylight
at least once per year, and a period of twenty-four hours' continuous night time
at least once per year. That is to say, there is at least one whole day during which the sun does not set, and at least one whole day during which the sun does not rise. On the Antarctic Circle these events occur, in principle, exactly once per year, at the December and June solstice
s respectively. This happens because the Earth's axis is tilted, by approximately 23.5 degrees, relative to ecliptic
(the plane of the Earth's orbit around the sun). At the southern winter solstice
, the southern hemisphere
is tilted away from the Sun to its maximum extent, and the region of permanent darkness reaches its northern limit; at the southern summer solstice
, the southern hemisphere is tilted towards the Sun to its maximum extent, and the region of permanent sunlight reaches its northern limit.
In practice several other factors affect the appearance of continuous day or night, the most important being atmospheric refraction
, the altitude of the observer above sea level, mirage
s, and the fact that the sun is a sphere rather than a point. Mirages on the Antarctic continent tend to be even more spectacular than in Arctic regions, creating, for example, a series of apparent sunsets and sunrises while in reality the sun remains under the horizon.
Due to gradual changes in the tilt of the Earth's axis, the Antarctic Circle is slowly moving. See circles of latitude.
of Antarctica forms a land mass covering much of the area within the Antarctic Circle. There is no permanent human population on Earth south of the Antarctic Circle. There are, however, several Antarctic research centers from various nations that are inhabited by teams of scientists that rotate on a seasonal basis. In previous centuries, some semi-permanent whaling stations were established on the continent and some of the whalers would live there for a year or more. At least three children have been born in Antarctica, albeit in stations north of the Antarctic Circle. See Demographics of Antarctica
.
Starting at the Prime Meridian
and heading eastwards, the Antarctic Circle passes through:
Circle of latitude
A circle of latitude, on the Earth, is an imaginary east-west circle connecting all locations that share a given latitude...
that mark maps of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. For 2011, it is the parallel of latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
that runs south of the Equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
.
Description
The area south of the Antarctic Circle is known as the AntarcticAntarctic
The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...
, and the zone immediately to the north is called the Southern Temperate Zone
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
. The equivalent line of latitude in the northern hemisphere is the Arctic Circle
Arctic Circle
The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. For Epoch 2011, it is the parallel of latitude that runs north of the Equator....
.
Every place south of the Antarctic Circle experiences a period of twenty-four hours' continuous daylight
Midnight sun
The midnight sun is a natural phenomenon occurring in summer months at latitudes north and nearby to the south of the Arctic Circle, and south and nearby to the north of the Antarctic Circle where the sun remains visible at the local midnight. Given fair weather, the sun is visible for a continuous...
at least once per year, and a period of twenty-four hours' continuous night time
Polar night
The polar night occurs when the night lasts for more than 24 hours. This occurs only inside the polar circles. The opposite phenomenon, the polar day, or midnight sun, occurs when the sun stays above the horizon for more than 24 hours.-Description:...
at least once per year. That is to say, there is at least one whole day during which the sun does not set, and at least one whole day during which the sun does not rise. On the Antarctic Circle these events occur, in principle, exactly once per year, at the December and June solstice
Solstice
A solstice is an astronomical event that happens twice each year when the Sun's apparent position in the sky, as viewed from Earth, reaches its northernmost or southernmost extremes...
s respectively. This happens because the Earth's axis is tilted, by approximately 23.5 degrees, relative to ecliptic
Ecliptic
The ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun...
(the plane of the Earth's orbit around the sun). At the southern winter solstice
Winter solstice
Winter solstice may refer to:* Winter solstice, astronomical event* Winter Solstice , former band* Winter Solstice: North , seasonal songs* Winter Solstice , 2005 American film...
, the southern hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
is tilted away from the Sun to its maximum extent, and the region of permanent darkness reaches its northern limit; at the southern summer solstice
Summer solstice
The summer solstice occurs exactly when the axial tilt of a planet's semi-axis in a given hemisphere is most inclined towards the star that it orbits. Earth's maximum axial tilt to our star, the Sun, during a solstice is 23° 26'. Though the summer solstice is an instant in time, the term is also...
, the southern hemisphere is tilted towards the Sun to its maximum extent, and the region of permanent sunlight reaches its northern limit.
In practice several other factors affect the appearance of continuous day or night, the most important being atmospheric refraction
Atmospheric refraction
Atmospheric refraction is the deviation of light or other things like humanelectromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of altitude...
, the altitude of the observer above sea level, mirage
Mirage
A mirage is a naturally occurring optical phenomenon in which light rays are bent to produce a displaced image of distant objects or the sky. The word comes to English via the French mirage, from the Latin mirare, meaning "to look at, to wonder at"...
s, and the fact that the sun is a sphere rather than a point. Mirages on the Antarctic continent tend to be even more spectacular than in Arctic regions, creating, for example, a series of apparent sunsets and sunrises while in reality the sun remains under the horizon.
Due to gradual changes in the tilt of the Earth's axis, the Antarctic Circle is slowly moving. See circles of latitude.
Geography and demographics
The continentContinent
A continent is one of several very large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents—they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia.Plate tectonics is...
of Antarctica forms a land mass covering much of the area within the Antarctic Circle. There is no permanent human population on Earth south of the Antarctic Circle. There are, however, several Antarctic research centers from various nations that are inhabited by teams of scientists that rotate on a seasonal basis. In previous centuries, some semi-permanent whaling stations were established on the continent and some of the whalers would live there for a year or more. At least three children have been born in Antarctica, albeit in stations north of the Antarctic Circle. See Demographics of Antarctica
Demographics of Antarctica
Antarctica has no indigenous inhabitants, but there are permanently and seasonally staffed research stations, field camps, and former whaling settlements. The largest of these, McMurdo Station, has a population of about 1200 residents...
.
Starting at the Prime Meridian
Prime Meridian
The Prime Meridian is the meridian at which the longitude is defined to be 0°.The Prime Meridian and its opposite the 180th meridian , which the International Date Line generally follows, form a great circle that divides the Earth into the Eastern and Western Hemispheres.An international...
and heading eastwards, the Antarctic Circle passes through:
| Co-ordinates | Country, territory or sea | Notes |
|---|---|---|
| 66°34′S 0°0′E | Southern Ocean Southern Ocean The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions... |
North of Queen Maud Land Queen Maud Land Queen Maud Land is a c. 2.7 million-square-kilometre region of Antarctica claimed as a dependent territory by Norway. The territory lies between 20° west and 45° east, between the British Antarctic Territory to the west and the Australian Antarctic Territory to the east. The latitudinal... and Enderby Land Enderby Land Enderby Land is a projecting land mass of Antarctica, extending from Shinnan Glacier at to William Scoresby Bay at .Enderby Land was discovered in February 1831 by John Biscoe in the whaling brig Tula, and named after the Enderby Brothers of London, owners of the Tula, who encouraged their... |
| 66°34′S 50°32′E | Antarctica – Enderby Land Enderby Land Enderby Land is a projecting land mass of Antarctica, extending from Shinnan Glacier at to William Scoresby Bay at .Enderby Land was discovered in February 1831 by John Biscoe in the whaling brig Tula, and named after the Enderby Brothers of London, owners of the Tula, who encouraged their... |
Territory claimed by |
| 66°34′S 57°19′E | Southern Ocean Southern Ocean The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions... |
North of the Amery Ice Shelf Amery Ice Shelf The Amery Ice Shelf is a broad ice shelf in Antarctica at the head of Prydz Bay between the Lars Christensen Coast and Ingrid Christensen Coast. It is part of Mac. Robertson Land. The name "Cape Amery" was applied to a coastal angle mapped on February 11, 1931 by the British Australian New Zealand... |
| 66°34′S 82°6′E | Antarctica | Territory claimed by |
| 66°34′S 89°14′E | Southern Ocean Southern Ocean The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions... |
|
| 66°34′S 91°29′E | Antarctica | Territory claimed by |
| 66°34′S 92°21′E | Southern Ocean Southern Ocean The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions... |
|
| 66°34′S 93°52′E | Antarctica | Territory claimed by |
| 66°34′S 107°45′E | Southern Ocean Southern Ocean The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions... |
Vincennes Bay Vincennes Bay Vincennes Bay is a large V-shaped bay, 105 km wide at its entrance between Cape Nutt and Cape Folger in Antarctica, marked by several large, steep glaciers near its head, lying along Knox and Budd Coasts. Photographed from the air by USN OpHjp, 1946-47... |
| 66°34′S 110°12′E | Antarctica – Wilkes Land Wilkes Land Wilkes Land is a large district of land in eastern Antarctica, formally claimed by Australia as part of the Australian Antarctic Territory, though the validity of this claim has been placed for the period of the operation of the Antarctic Treaty, to which Australia is a signatory... |
Territory claimed by |
| 66°34′S 116°35′E | Southern Ocean Southern Ocean The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions... |
|
| 66°34′S 121°31′E | Antarctica – Wilkes Land Wilkes Land Wilkes Land is a large district of land in eastern Antarctica, formally claimed by Australia as part of the Australian Antarctic Territory, though the validity of this claim has been placed for the period of the operation of the Antarctic Treaty, to which Australia is a signatory... |
Territory claimed by |
| 66°34′S 127°9′E | Southern Ocean Southern Ocean The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions... |
|
| 66°34′S 129°38′E | Antarctica – Wilkes Land Wilkes Land Wilkes Land is a large district of land in eastern Antarctica, formally claimed by Australia as part of the Australian Antarctic Territory, though the validity of this claim has been placed for the period of the operation of the Antarctic Treaty, to which Australia is a signatory... |
Territory claimed by |
| 66°34′S 136°0′E | Antarctica – Adélie Land Adélie Land Adélie Land is the portion of the Antarctic coast between 136° E and 142° E , with a shore length of 350 km and with its hinterland extending as a sector about 2,600 km toward the South Pole. It is claimed by France as one of five districts of the French Southern and Antarctic Lands, although not... |
Territory claimed by |
| 66°34′S 138°56′E | Southern Ocean Southern Ocean The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions... |
|
| 66°34′S 162°44′E | Balleny Islands Balleny Islands The Balleny Islands are a series of uninhabited islands in the Southern Ocean extending from 66°15' to 67°35'S and 162°30' to 165°00'E. The group extends for about in a northwest-southeast direction. The islands are heavily glaciated and are of volcanic origin. Glaciers project from their slopes... – Borradaile Island Borradaile Island Borradaile Island is one of the Balleny Islands. It was the site of the first landing south of the Antarctic Circle, and features the "remarkable pinnacle" called Beale Pinnacle, near Cape Beale on its south-eastern coast, and Cape Scoresby on its north-western coast.-Exploration:Borradaile Island... |
Territory claimed by |
| 66°34′S 162°45′E | Southern Ocean Southern Ocean The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions... |
Passing just north of Adelaide Island Adelaide Island Adelaide Island or Isla Adelaida or Isla Belgrano is a large, mainly ice-covered island, long and wide, lying at the north side of Marguerite Bay off the west coast of the Antarctic Peninsula. The island lies within the Argentine, British and Chilean Antarctic claims, at .Adelaide Island was... (claimed by , and ) |
| 66°34′S 65°44′W | Antarctica – Antarctic Peninsula Antarctic Peninsula The Antarctic Peninsula is the northernmost part of the mainland of Antarctica. It extends from a line between Cape Adams and a point on the mainland south of Eklund Islands.... – Graham Land Graham Land Graham Land is that portion of the Antarctic Peninsula which lies north of a line joining Cape Jeremy and Cape Agassiz. This description of Graham Land is consistent with the 1964 agreement between the British Antarctic Place-names Committee and the US Advisory Committee on Antarctic Names, in... and Larsen Ice Shelf Larsen Ice Shelf The Larsen Ice Shelf is a long, fringing ice shelf in the northwest part of the Weddell Sea, extending along the east coast of Antarctic Peninsula from Cape Longing to the area just southward of Hearst Island... |
Territory claimed by , and |
| 66°34′S 60°21′W | Southern Ocean Southern Ocean The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions... |
Passing through the Weddell Sea Weddell Sea The Weddell Sea is part of the Southern Ocean and contains the Weddell Gyre. Its land boundaries are defined by the bay formed from the coasts of Coats Land and the Antarctic Peninsula. The easternmost point is Cape Norvegia at Princess Martha Coast, Queen Maud Land. To the east of Cape Norvegia is... and into an unnamed part of the ocean |
See also
- Arctic CircleArctic CircleThe Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. For Epoch 2011, it is the parallel of latitude that runs north of the Equator....
- EquatorEquatorAn equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
- Antarctic ConvergenceAntarctic ConvergenceThe Antarctic Convergence is a curve continuously encircling Antarctica where cold, northward-flowing Antarctic waters meet the relatively warmer waters of the subantarctic. Antarctic waters predominantly sink beneath subantarctic waters, while associated zones of mixing and upwelling create a zone...
- SolsticeSolsticeA solstice is an astronomical event that happens twice each year when the Sun's apparent position in the sky, as viewed from Earth, reaches its northernmost or southernmost extremes...
- Obliquity of the EclipticAxial tiltIn astronomy, axial tilt is the angle between an object's rotational axis, and a line perpendicular to its orbital plane...
- Tropic of CancerTropic of CancerThe Tropic of Cancer, also referred to as the Northern tropic, is the circle of latitude on the Earth that marks the most northerly position at which the Sun may appear directly overhead at its zenith...
- Tropic of CapricornTropic of CapricornThe Tropic of Capricorn, or Southern tropic, marks the most southerly latitude on the Earth at which the Sun can be directly overhead. This event occurs at the December solstice, when the southern hemisphere is tilted towards the Sun to its maximum extent.Tropic of Capricorn is one of the five...