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41-561: The Canadian Arctic Expedition 1913–1916 was a scientific expedition in the Arctic Circle organized and led by Vilhjalmur Stefansson . The expedition was originally to be sponsored by the (US) National Geographic Society and the American Museum of Natural History . Canada took over the sponsorship because of the potential for discovery of new land and Stefansson, who though born in Canada

82-485: A meridian (a great circle passing through the two poles). The IUGG standard meridian is, to the nearest millimetre, 40,007.862917 kilometres (24,859.733480 mi), one arc-minute of which is 1,852.216 metres (6,076.82 ft), explaining the SI standardization of the nautical mile as 1,852 metres (6,076 ft), more than 3 metres (9.8 ft) less than the geographical mile . The sea-level surface of Earth (the geoid )

123-543: A small continent, was scientifically plausible. The approach of the Northern Party, besides simply going out and looking for land, was a program of through-ice depth soundings to map the edge of the continental shelf. Meteorological, magnetic, and marine biological investigations were also planned. The objective of the Southern Party was scientific documentation of the geography, geology, resources, wildlife, and people of

164-451: Is a standard for use in cartography, geodesy, and satellite navigation including GPS , also has an equatorial radius of 6,378.137 km (3,963.191 mi). For both GRS 80 and WGS 84, this results in a length for the Equator of 40,075.0167 km (24,901.4609 mi). The geographical mile is defined as one arc-minute of the Equator, so it has different values depending on which radius

205-495: Is also a great circle —meaning, one whose plane passes through the center of the globe. The plane of Earth's equator, when projected outwards to the celestial sphere , defines the celestial equator . In the cycle of Earth's seasons , the equatorial plane runs through the Sun twice a year : on the equinoxes in March and September . To a person on Earth, the Sun appears to travel along

246-406: Is assumed. For example, by WSG-84, the distance is 1,855.3248 metres (6,087.024 ft), while by IAU-2000, it is 1,855.3257 metres (6,087.027 ft). This is a difference of less than one millimetre (0.039 in) over the total distance (approximately 1.86 kilometres or 1.16 miles). Earth is commonly modeled as a sphere flattened 0.336% along its axis. This makes the Equator 0.16% longer than

287-458: Is irregular, so the actual length of the Equator is not so easy to determine. Aviation Week and Space Technology on 9 October 1961 reported that measurements using the Transit IV-A satellite had shown the equatorial diameter from longitude 11° West to 169° East to be 1,000 feet (305 m) greater than its diameter ninety degrees away. Download coordinates as: The Equator passes through

328-613: Is often no direct view of the true horizon. The largest communities north of the Arctic Circle are situated in Russia, Norway, and Sweden: Murmansk (population 295,374) and Norilsk (178,018) in Russia; Tromsø (75,638) in Norway, Vorkuta (58,133) in Russia, Bodø (52,357) and Harstad (24,703) in Norway; and Kiruna , Sweden (22,841). Rovaniemi (62,667) in Finland is the largest settlement in

369-557: Is perpendicular to the Earth's rotation axis , which drifts about 9 metres (30 ft) during a year. Geological samples show that the Equator significantly changed positions between 48 and 12 million years ago, as sediment deposited by ocean thermal currents at the Equator shifted. The deposits by thermal currents are determined by the axis of Earth, which determines solar coverage of Earth's surface . Changes in Earth's axis can also be observed in

410-622: Is the largest settlement north of the Arctic Circle with about 5,000 inhabitants. The largest such community in Canada is Inuvik in the Northwest Territories , with 3,137 inhabitants. Download coordinates as: The Arctic Circle is roughly 16,000 km (9,900 mi) in circumference. The area north of the Circle is about 20,000,000 km (7,700,000 sq mi) and covers roughly 4% of Earth's surface. The Arctic Circle passes through

451-429: Is tilted towards or away from the sun, resulting in either summer or winter in both hemispheres. This also results in a corresponding movement of the equator away from the subsolar point, which is then situated over or near the relevant tropic circle . Nevertheless, temperatures are high year-round due to the Earth's axial tilt of 23.5° not being enough to create a low minimum midday declination to sufficiently weaken

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492-585: The Arctic Ocean , the Scandinavian Peninsula , North Asia , Northern America , and Greenland. The land within the Arctic Circle is divided among eight countries: Norway, Sweden, Finland, Russia, the United States ( Alaska ), Canada ( Yukon , Northwest Territories , and Nunavut ), Denmark (Greenland), and Iceland (where it passes through the small offshore island of Grímsey ). The climate north of

533-581: The Latin word aequare 'make equal'. The latitude of the Earth's equator is, by definition, 0° (zero degrees ) of arc. The equator is one of the five notable circles of latitude on Earth; the other four are the two polar circles (the Arctic Circle and the Antarctic Circle ) and the two tropical circles (the Tropic of Cancer and the Tropic of Capricorn ). The equator is the only line of latitude which

574-565: The Mackenzie River delta and adjacent regions of Canada between Cape Parry and the Kent Peninsula , for about 100 mi (160 km) inland, and southern and eastern Victoria Island . Copper deposits and trade routes were of particular interest. 1913 was a particularly bad year for Arctic navigation. All of the expedition ships were frozen in before they could reach their initial destination of Herschel Island . The principal ship of

615-603: The orbit of the Moon . Consequently, the Arctic Circle is currently drifting northwards at a speed of about 14.5 m (48 ft) per year. The word arctic comes from the Greek word ἀρκτικός ( arktikos : "near the Bear , northern") and that from the word ἄρκτος ( arktos : " bear "). The Arctic Circle is the southernmost latitude in the Northern Hemisphere at which the centre of

656-522: The winter solstice (which is the shortest day of the year) in the Northern Hemisphere , the Sun will not rise all day, and on the Northern Hemisphere's summer solstice (which is the longest day of the year), the Sun will not set. These phenomena are referred to as polar night and midnight sun respectively, and the further north one progresses, the more pronounced these effects become. For example, in

697-515: The Arctic Circle is generally cold, but the coastal areas of Norway have a generally mild climate as a result of the Gulf Stream , which makes the ports of northern Norway and northwest Russia ice-free all year long. In the interior, summers can be quite warm, while winters are extremely cold. For example, summer temperatures in Norilsk , Russia will sometimes reach as high as 30 °C (86 °F), while

738-486: The Equator has a rather stable daytime temperature throughout the year. On the equinoxes (approximately March 20 and September 23) the subsolar point crosses Earth's equator at a shallow angle, sunlight shines perpendicular to Earth's axis of rotation, and all latitudes have nearly a 12-hour day and 12-hour night. The name is derived from medieval Latin word aequator , in the phrase circulus aequator diei et noctis , meaning 'circle equalizing day and night', from

779-549: The Equator. However, its island of Annobón is 155 km (96 mi) south of the Equator, and the rest of the country lies to the north. France , Norway ( Bouvet Island ), and the United Kingdom are the other three Northern Hemisphere -based countries which have territories in the Southern Hemisphere . Seasons result from the tilt of Earth's axis away from a line perpendicular to the plane of its revolution around

820-686: The IAU 2009 value). This equatorial radius is also in the 2003 and 2010 IERS Conventions. It is also the equatorial radius used for the IERS 2003 ellipsoid. If it were really circular, the length of the equator would then be exactly 2π times the radius, namely 40,075.0142 km (24,901.4594 mi). The GRS 80 (Geodetic Reference System 1980) as approved and adopted by the IUGG at its Canberra, Australia meeting of 1979 has an equatorial radius of 6,378.137 km (3,963.191 mi). The WGS 84 (World Geodetic System 1984) which

861-526: The Russian port city of Murmansk , three degrees above the Arctic Circle, the Sun does not rise above the horizon for 40 successive days in midwinter. The position of the Arctic Circle is not fixed and currently runs 66°33′50.2″ north of the Equator . Its latitude depends on the Earth's axial tilt , which fluctuates within a margin of more than 2° over a 41,000-year period, owing to tidal forces resulting from

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902-543: The Sun can remain continuously above or below the horizon for twenty-four hours; as a result, at least once each year at any location within the Arctic Circle the centre of the Sun is visible at local midnight , and at least once the centre is not visible at local noon . Directly on the Arctic Circle these events occur, in principle, exactly once per year: at the June and December solstices , respectively. However, because of atmospheric refraction and mirages , and also because

943-513: The Sun's rays even during the solstices. High year-round temperatures extend to about 25° north or south of the equator, although the moderate seasonal temperature difference is defined by the opposing solstices (as it is at higher latitudes) near the poleward limits of this range. Near the equator, there is little temperature change throughout the year, though there may be dramatic differences in rainfall and humidity. The terms summer, autumn, winter and spring do not generally apply. Lowlands around

984-540: The Sun. Throughout the year, the Northern and Southern hemispheres are alternately turned either toward or away from the Sun, depending on Earth's position in its orbit. The hemisphere turned toward the Sun receives more sunlight and is in summer, while the other hemisphere receives less sun and is in winter (see solstice ). At the equinoxes , Earth's axis is perpendicular to the Sun rather than tilted toward or away, meaning that day and night are both about 12 hours long across

1025-473: The afternoon and 23 °C (73 °F) around sunrise. Rainfall is very high away from cold ocean current upwelling zones, from 2,500 to 3,500 mm (100 to 140 in) per year. There are about 200 rainy days per year and average annual sunshine hours are around 2,000. Despite high year-round sea level temperatures, some higher altitudes such as the Andes and Mount Kilimanjaro have glaciers. The highest point on

1066-412: The careers of several explorers and scientists. The controversies it engendered persisted for decades. Arctic Circle The Arctic Circle is one of the two polar circles , and the most northerly of the five major circles of latitude as shown on maps of Earth at about 66° 34' N. Its southern equivalent is the Antarctic Circle . The Arctic Circle marks the southernmost latitude at which, on

1107-446: The equator (or along the celestial equator) at these times. Locations on the equator experience the shortest sunrises and sunsets because the Sun's daily path is nearly perpendicular to the horizon for most of the year. The length of daylight (sunrise to sunset) is almost constant throughout the year; it is about 14 minutes longer than nighttime due to atmospheric refraction and the fact that sunrise begins (or sunset ends) as

1148-621: The equator generally have a tropical rainforest climate , also known as an equatorial climate, though cold ocean currents cause some regions to have tropical monsoon climates with a dry season in the middle of the year, and the Somali Current generated by the Asian monsoon due to continental heating via the high Tibetan Plateau causes Greater Somalia to have an arid climate despite its equatorial location. Average annual temperatures in equatorial lowlands are around 31 °C (88 °F) during

1189-468: The equator is at the elevation of 4,690 metres (15,387 ft), at 0°0′0″N 77°59′31″W  /  0.00000°N 77.99194°W  / 0.00000; -77.99194  ( highest point on the equator ) , found on the southern slopes of Volcán Cayambe [summit 5,790 metres (18,996 ft)] in Ecuador . This is slightly above the snow line and is the only place on the equator where snow lies on

1230-606: The expedition, the Karluk , was carried off and eventually crushed by the ice , leading to the loss of eleven lives before a famous rescue. Most of the Southern Party had travelled in other ships of the expedition, and Stefansson left the Karluk with a party of five before the ship was carried off. Stefansson promptly purchased a small schooner , the North Star , reconstituted the Northern Party with local hires and resumed exploring. Only one of

1271-465: The fastest rotational speed of any latitude, 460 m (1,509 ft)/sec. The added velocity reduces the fuel needed to launch spacecraft eastward (in the direction of Earth's rotation) to orbit, while simultaneously avoiding costly maneuvers to flatten inclination during missions such as the Apollo Moon landings . The precise location of the Equator is not truly fixed; the true equatorial plane

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1312-666: The fourteen Karluk survivors rejoined the expedition. The expedition purchased another ship, the Polar Bear , in 1915. The Southern Party remained in the North through the summer of 1916, exploring and mapping as far east as Bathurst Inlet . Some members of the Northern Party continued exploring through 1918. The expedition discovered land previously unknown even to the Inuit (including Brock , Mackenzie King , Borden , Meighen , Lougheed and Stefansson Islands ), produced valuable data, and launched

1353-679: The geographical layout of volcanic island chains, which are created by shifting hot spots under Earth's crust as the axis and crust move. This is consistent with the Indian tectonic plate colliding with the Eurasian tectonic plate , which is causing the Himalayan uplift. The International Association of Geodesy (IAG) and the International Astronomical Union (IAU) use an equatorial radius of 6,378.1366 km (3,963.1903 mi) (codified as

1394-404: The immediate vicinity of the Arctic Circle, lying 6 km (4 mi) south of the line. Salekhard (51,186) in Russia is the only city in the world located directly on the Arctic Circle. In contrast, the largest North American community north of the Arctic Circle, Sisimiut ( Greenland ), has approximately 5,600 inhabitants. In the United States, Utqiagvik, Alaska (formerly known as Barrow)

1435-611: The land of eleven sovereign states . Indonesia is the country straddling the greatest length of the equatorial line across both land and sea. Starting at the Prime Meridian and heading eastwards, the Equator passes through: The Equator also passes through the territorial seas of three countries: Maldives (south of Gaafu Dhaalu Atoll ), Kiribati (south of Buariki Island ), and the United States (south of Baker Island ). Despite its name, no part of Equatorial Guinea lies on

1476-425: The spheroid, equidistant from its poles , dividing it into northern and southern hemispheres. In other words, it is the intersection of the spheroid with the plane perpendicular to its axis of rotation and midway between its geographical poles . On and near the Equator (on Earth), noontime sunlight appears almost directly overhead (no more than about 23° from the zenith ) every day, year-round. Consequently,

1517-480: The sun appears as a disk and not a point, part of the midnight sun is visible, on the night of the northern summer solstice , at a latitude of about 50 minutes of arc (′) (90 km (56 mi)) south of the Arctic Circle. Similarly, on the day of the northern winter solstice , part of the Sun may be seen up to about 50′ north of the Arctic Circle. That is true at sea level ; those limits increase with elevation above sea level , although in mountainous regions there

1558-510: The upper limb, not the center, of the Sun's disk contacts the horizon. Earth bulges slightly at the Equator; its average diameter is 12,742 km (7,918 mi), but the diameter at the equator is about 43 km (27 mi) greater than at the poles. Sites near the Equator, such as the Guiana Space Centre in Kourou , French Guiana , are good locations for spaceports as they have

1599-445: The whole of Earth. Near the equator, this means the variation in the strength of solar radiation is different relative to the time of year than it is at higher latitudes: maximum solar radiation is received during the equinoxes, when a place at the equator is under the subsolar point at high noon, and the intermediate seasons of spring and autumn occur at higher latitudes; and the minimum occurs during both solstices, when either pole

1640-403: The winter temperatures frequently fall below −50 °C (−58 °F). Starting at the prime meridian and heading eastwards, the Arctic Circle passes through: Equator In spatial (3D) geometry , as applied in astronomy , the equator of a rotating spheroid (such as a planet ) is the parallel (circle of latitude) at which latitude is defined to be 0°. It is an imaginary line on

1681-480: Was now an American, re-established his Canadian citizenship. The expedition was divided into a Northern Party led by Stefansson, and a Southern Party led by R M. Anderson . The objective of the Northern Party was to explore for new land north and west of the known lands of the Canadian Arctic . At this time the possible existence of large undiscovered land masses, comparable to the Canadian Arctic islands or even

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