23°26′12.5″N 0°0′0″W / 23.436806°N -0.00000°E
The Tropic of Cancer, also known as the Northern Tropic, is the Earth's northernmost circle of latitude where the Sun can be seen directly overhead. This occurs on the June solstice, when the Northern Hemisphere is tilted toward the Sun to its maximum extent. It also reaches 90 degrees below the horizon at solar midnight on the December Solstice. Using a continuously updated formula, the circle is currently 23°26′09.7″ (or 23.43602°) north of the Equator.
Its Southern Hemisphere counterpart, marking the most southerly position at which the Sun can be seen directly overhead, is the Tropic of Capricorn. These tropics are two of the five major circles of latitude that mark maps of Earth, the others being the Arctic and Antarctic circles and the Equator. The positions of these two circles of latitude (relative to the Equator) are dictated by the tilt of Earth's axis of rotation relative to the plane of its orbit, and since the tilt changes, the location of these two circles also changes.
In geopolitics, it is known for being the southern limitation on the mutual defence obligation of NATO, as member states of NATO are not obligated to come to the defence of territory south of the Tropic of Cancer.
Name
When this line of latitude was named in the last centuries BCE, the Sun was in the constellation Cancer (Latin: Crab) at the June solstice (90° ecliptic longitude). Due to the precession of the equinoxes, this is no longer the case; today the Sun is in constellation Taurus at the June solstice. The word "tropic" itself comes from the Greek "trope (τροπή)", meaning turn (change of direction or circumstance), inclination, referring to the fact that the Sun appears to "turn back" at the solstices.
Drift
The Tropic of Cancer's position is not fixed, but constantly changes because of a slight wobble in the Earth's longitudinal alignment relative to the ecliptic, the plane in which the Earth orbits around the Sun. Earth's axial tilt varies over a 41,000-year period from about 22.1 to 24.5 degrees, and as of 2000[update] is about 23.4 degrees, which will continue to remain valid for about a millennium. This wobble means that the Tropic of Cancer is currently drifting southward at a rate of almost half an arcsecond (0.468″) of latitude, or 15 m (49 ft), per year. The circle's position was at exactly 23° 27′N in 1917 and will be at 23° 26'N in 2045.
The distance between the Antarctic Circle and the Tropic of Cancer is essentially constant as they move in tandem. This is based on an assumption of a constant equator, but the precise location of the equator is not truly fixed. See: equator, axial tilt and circles of latitude for additional details.
Geography
North of the tropic are the subtropics and the North Temperate Zone. The equivalent line of latitude south of the Equator is called the Tropic of Capricorn, and the region between the two, centered on the Equator, is the tropics.
In the year 2000, more than half of the world's population lived north of the Tropic of Cancer.
On the Tropic of Cancer there are approximately 13 hours, 35 minutes of daylight during the summer solstice. During the winter solstice, there are 10 hours, 41 minutes of daylight.
Using 23°26'N for the Tropic of Cancer, the tropic passes through the following 17 countries (including two disputed territories) and 8 water bodies, starting at the prime meridian and heading eastward:
Climate
The climate at the Tropic of Cancer is generally hot and dry, except for cooler highland regions in China, marine environments such as Hawaii, and easterly coastal areas, where orographic rainfall can be very heavy, in some places reaching 4 metres (160 in) annually. Most regions on the Tropic of Cancer experience two distinct seasons: an extremely hot summer with temperatures often reaching 45 °C (113 °F) and a warm winter with maxima around 22 °C (72 °F). Much land on or near the Tropic of Cancer is part of the Sahara Desert, while to the east, the climate is torrid monsoonal with a short wet season from June to September, and very little rainfall for the rest of the year.
The highest mountain on or adjacent to the Tropic of Cancer is Yu Shan in Taiwan. It had glaciers descending as low as 2,800 metres (9,190 ft) during the Last Glacial Maximum. At present glaciers still exist around the Tropic. The nearest currently surviving are the and in the Himalayas to the north and on Pico de Orizaba in Mexico to the south.
Circumnavigation
According to the rules of the Fédération Aéronautique Internationale, for a flight to compete for a round-the-world speed record, it must cover a distance no less than the length of the Tropic of Cancer, cross all meridians, and end on the same airfield where it started.
The length of the Tropic of Cancer is 36,788 km (22,859 mi):
- where φ is the latitude of the Tropic of Cancer
For an ordinary circumnavigation the rules are somewhat relaxed and the distance is set to a rounded value of at least 36,770 kilometres (22,850 mi).
Gallery
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Road sign south of Dakhla, marking the Tropic of Cancer. The sign was placed by Budapest-Bamako rally participants; thus, the inscription is in English and Hungarian. -
Road Sign near Mehsana City in Gujarat State, India Mehsana, Gujarat -
Sign marking the Tropic of Cancer a few kilometres from Rann of Kutch, Gujarat, India -
Sign marking the Tropic of Cancer in Madhya Pradesh, India -
Sign marking the Tropic of Cancer on National Highway 34 in Nadia District, West Bengal, India -
Ruisui Tropic of Cancer Marker in Ruisui Township, Hualien County, Taiwan -
Tower of the Tropic of Cancer in Guangzhou, Guangdong Province, China
See also
- Circle of latitude
- Arctic Circle
- 24th parallel north
- 23rd parallel north
- Equator
- Tropic of Capricorn
- Antarctic Circle
- Axial tilt
- Milankovitch cycles
References
- "Obliquity of the Ecliptic and Arctic Circle Calculator". Retrieved September 20, 2022.
- "NATO - Topic: Collective defence and Article 5". North Atlantic Treaty Organization. Retrieved 4 April 2024.
- Montana State University: Milankovitch Cycles & Glaciation Archived August 6, 2011, at the Wayback Machine
- Quigley, Robert (12 August 2010). "The World's Population Mapped by Latitude and Longitude". The Mary Sue. Retrieved 11 January 2021.
- within 470 kilometres (290 mi)
- Bakker et al., Radio Positioning at Sea: Geodetic Survey Computations Least Squares Adjustment, 1995 (ISBN 90-6275-537-2)
External links
- Temporal Epoch Calculations
- Useful constants (see: Obliquity of the ecliptic)
23 26 12 5 N 0 0 0 W 23 436806 N 0 00000 E 23 436806 0 00000 Prime Meridian World map showing the Tropic of CancerRelationship of Earth s axial tilt e to the tropical and polar circles The Tropic of Cancer also known as the Northern Tropic is the Earth s northernmost circle of latitude where the Sun can be seen directly overhead This occurs on the June solstice when the Northern Hemisphere is tilted toward the Sun to its maximum extent It also reaches 90 degrees below the horizon at solar midnight on the December Solstice Using a continuously updated formula the circle is currently 23 26 09 7 or 23 43602 north of the Equator Its Southern Hemisphere counterpart marking the most southerly position at which the Sun can be seen directly overhead is the Tropic of Capricorn These tropics are two of the five major circles of latitude that mark maps of Earth the others being the Arctic and Antarctic circles and the Equator The positions of these two circles of latitude relative to the Equator are dictated by the tilt of Earth s axis of rotation relative to the plane of its orbit and since the tilt changes the location of these two circles also changes In geopolitics it is known for being the southern limitation on the mutual defence obligation of NATO as member states of NATO are not obligated to come to the defence of territory south of the Tropic of Cancer NameWhen this line of latitude was named in the last centuries BCE the Sun was in the constellation Cancer Latin Crab at the June solstice 90 ecliptic longitude Due to the precession of the equinoxes this is no longer the case today the Sun is in constellation Taurus at the June solstice The word tropic itself comes from the Greek trope troph meaning turn change of direction or circumstance inclination referring to the fact that the Sun appears to turn back at the solstices DriftCarretera 83 Via Corta Zaragoza Victoria km 27 800 Of the Tropic of Cancer s intersections with Mexican federal highways this is the only one where it is precisely marked and the drift from 2005 to 2010 can be seen The Tropic of Cancer s position is not fixed but constantly changes because of a slight wobble in the Earth s longitudinal alignment relative to the ecliptic the plane in which the Earth orbits around the Sun Earth s axial tilt varies over a 41 000 year period from about 22 1 to 24 5 degrees and as of 2000 update is about 23 4 degrees which will continue to remain valid for about a millennium This wobble means that the Tropic of Cancer is currently drifting southward at a rate of almost half an arcsecond 0 468 of latitude or 15 m 49 ft per year The circle s position was at exactly 23 27 N in 1917 and will be at 23 26 N in 2045 The distance between the Antarctic Circle and the Tropic of Cancer is essentially constant as they move in tandem This is based on an assumption of a constant equator but the precise location of the equator is not truly fixed See equator axial tilt and circles of latitude for additional details GeographyMap all coordinates using OpenStreetMap Download coordinates as KML GPX all coordinates GPX primary coordinates GPX secondary coordinates North of the tropic are the subtropics and the North Temperate Zone The equivalent line of latitude south of the Equator is called the Tropic of Capricorn and the region between the two centered on the Equator is the tropics In the year 2000 more than half of the world s population lived north of the Tropic of Cancer On the Tropic of Cancer there are approximately 13 hours 35 minutes of daylight during the summer solstice During the winter solstice there are 10 hours 41 minutes of daylight Using 23 26 N for the Tropic of Cancer the tropic passes through the following 17 countries including two disputed territories and 8 water bodies starting at the prime meridian and heading eastward Coordinates 1 accuracy 2 km 1 mi Country territory or sea Notes23 26 N 0 0 E 23 433 N 0 000 E 23 433 0 000 Prime Meridian Algeria23 26 N 11 51 E 23 433 N 11 850 E 23 433 11 850 Niger Niger23 26 N 12 17 E 23 433 N 12 283 E 23 433 12 283 Libya Libya The Tropic touches on the northernmost point of Chad at 23 26 N 15 59 E 23 433 N 15 983 E 23 433 15 983 Northernmost point of Chad 23 26 N 25 0 E 23 433 N 25 000 E 23 433 25 000 Egypt Egypt The Tropic passes through Lake Nasser23 26 N 35 30 E 23 433 N 35 500 E 23 433 35 500 Red Sea Red Sea23 26 N 38 38 E 23 433 N 38 633 E 23 433 38 633 Saudi Arabia Saudi Arabia AlMedinah Mecca ArRiyadh and The Eastern provinces 23 26 N 52 10 E 23 433 N 52 167 E 23 433 52 167 United Arab Emirates United Arab Emirates Abu Dhabi emirate only23 26 N 55 24 E 23 433 N 55 400 E 23 433 55 400 Oman Oman The tropic crosses Muscat the country s capital 23 26 N 58 46 E 23 433 N 58 767 E 23 433 58 767 Indian Ocean Indian Ocean Arabian Sea23 26 N 68 23 E 23 433 N 68 383 E 23 433 68 383 India India States of Gujarat Rajasthan Madhya Pradesh Chhattisgarh Jharkhand and West Bengal23 26 N 88 47 E 23 433 N 88 783 E 23 433 88 783 Bangladesh Bangladesh Khulna Dhaka and Chittagong divisions23 26 N 91 14 E 23 433 N 91 233 E 23 433 91 233 India India State of Tripura23 26 N 91 56 E 23 433 N 91 933 E 23 433 91 933 Bangladesh Bangladesh Chittagong Division23 26 N 92 19 E 23 433 N 92 317 E 23 433 92 317 India India State of Mizoram23 26 N 93 23 E 23 433 N 93 383 E 23 433 93 383 Myanmar Myanmar Chin State Sagaing Division Mandalay Division Shan State23 26 N 98 54 E 23 433 N 98 900 E 23 433 98 900 China China Provinces of Yunnan passing about 7 km north of the border with Vietnam Guangxi and Guangdong23 26 N 117 8 E 23 433 N 117 133 E 23 433 117 133 Taiwan Strait Taiwan Strait23 26 N 120 8 E 23 433 N 120 133 E 23 433 120 133 Taiwan Taiwan Hujing Island Huching Island Chiayi County Hualien County23 26 N 121 29 E 23 433 N 121 483 E 23 433 121 483 Philippine Sea Philippine Sea23 26 N 142 00 E 23 433 N 142 000 E 23 433 142 000 Pacific Ocean Pacific Ocean Passing just south of Necker Island Hawaii United States23 26 N 110 15 W 23 433 N 110 250 W 23 433 110 250 Mexico Mexico State of Baja California Sur23 26 N 109 24 W 23 433 N 109 400 W 23 433 109 400 Gulf of California Gulf of California23 26 N 106 35 W 23 433 N 106 583 W 23 433 106 583 Mexico Mexico States of Sinaloa Durango Zacatecas San Luis Potosi Nuevo Leon and Tamaulipas23 26 N 97 45 W 23 433 N 97 750 W 23 433 97 750 Gulf of Mexico Gulf of Mexico Passing just north of Cuba23 26 N 83 0 W 23 433 N 83 000 W 23 433 83 000 Atlantic Ocean Atlantic Ocean Passing through the Straits of Florida and the Nicholas Channel Passing just south of the Anguilla Cays Bahamas Passing through the Santaren Channel and into the open ocean23 26 N 76 0 W 23 433 N 76 000 W 23 433 76 000 Bahamas Bahamas Exuma Islands and Long Island23 26 N 75 10 W 23 433 N 75 167 W 23 433 75 167 Atlantic Ocean Atlantic Ocean23 26 N 15 57 W 23 433 N 15 950 W 23 433 15 950 Western Sahara Western Sahara Claimed by Morocco and the Sahrawi Republic23 26 N 12 0 W 23 433 N 12 000 W 23 433 12 000 Mauritania Mauritania23 26 N 6 23 W 23 433 N 6 383 W 23 433 6 383 Mali Mali23 26 N 2 23 W 23 433 N 2 383 W 23 433 2 383 Algeria AlgeriaClimateThe climate at the Tropic of Cancer is generally hot and dry except for cooler highland regions in China marine environments such as Hawaii and easterly coastal areas where orographic rainfall can be very heavy in some places reaching 4 metres 160 in annually Most regions on the Tropic of Cancer experience two distinct seasons an extremely hot summer with temperatures often reaching 45 C 113 F and a warm winter with maxima around 22 C 72 F Much land on or near the Tropic of Cancer is part of the Sahara Desert while to the east the climate is torrid monsoonal with a short wet season from June to September and very little rainfall for the rest of the year The highest mountain on or adjacent to the Tropic of Cancer is Yu Shan in Taiwan It had glaciers descending as low as 2 800 metres 9 190 ft during the Last Glacial Maximum At present glaciers still exist around the Tropic The nearest currently surviving are the and in the Himalayas to the north and on Pico de Orizaba in Mexico to the south CircumnavigationAccording to the rules of the Federation Aeronautique Internationale for a flight to compete for a round the world speed record it must cover a distance no less than the length of the Tropic of Cancer cross all meridians and end on the same airfield where it started The length of the Tropic of Cancer is 36 788 km 22 859 mi l 2pcos f 6378137 1 0 00669438 sin f 2 0 5 displaystyle l 2 pi cos varphi 6378137 1 0 00669438 sin varphi 2 0 5 where f is the latitude of the Tropic of Cancer For an ordinary circumnavigation the rules are somewhat relaxed and the distance is set to a rounded value of at least 36 770 kilometres 22 850 mi GalleryRoad sign south of Dakhla marking the Tropic of Cancer The sign was placed by Budapest Bamako rally participants thus the inscription is in English and Hungarian Road Sign near Mehsana City in Gujarat State India Mehsana Gujarat Sign marking the Tropic of Cancer a few kilometres from Rann of Kutch Gujarat India Sign marking the Tropic of Cancer in Madhya Pradesh India Sign marking the Tropic of Cancer on National Highway 34 in Nadia District West Bengal India Ruisui Tropic of Cancer Marker in Ruisui Township Hualien County Taiwan Tower of the Tropic of Cancer in Guangzhou Guangdong Province ChinaSee alsoGeography portalAfrica portalChina portalMexico portalCircle of latitude Arctic Circle 24th parallel north 23rd parallel north Equator Tropic of Capricorn Antarctic Circle Axial tilt Milankovitch cyclesReferences Obliquity of the Ecliptic and Arctic Circle Calculator Retrieved September 20 2022 NATO Topic Collective defence and Article 5 North Atlantic Treaty Organization Retrieved 4 April 2024 Montana State University Milankovitch Cycles amp Glaciation Archived August 6 2011 at the Wayback Machine Quigley Robert 12 August 2010 The World s Population Mapped by Latitude and Longitude The Mary Sue Retrieved 11 January 2021 within 470 kilometres 290 mi Bakker et al Radio Positioning at Sea Geodetic Survey Computations Least Squares Adjustment 1995 ISBN 90 6275 537 2 External linksWikimedia Commons has media related to Tropic of Cancer Look up Tropic of Cancer in Wiktionary the free dictionary Temporal Epoch Calculations Useful constants see Obliquity of the ecliptic
