Turning circle (latitude)
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On Earth, the tropics are the two latitudes of 23 ° 26 ′ 05 ″ (23.43472 °) north ( Tropic of Cancer ) and south ( Tropic of Capricorn ) latitude. On them the sun at noon of the day of the respective solstice in Zenit . The tropics are each 2,609 km away from the equator and are each around 36,700 km long. The belt between the northern and southern tropics is known as the tropics .
astronomy
In the sky, the tropics are circles parallel to the celestial equator . They touch the apparent annual orbit of the sun (the ecliptic ), which cuts the celestial equator at an angle and, like the equator, is also a great circle in the sky. Their angular distance from the celestial equator is also ± 23 ° 26'05 ". These are also the limit values for the so-called declination angle of the sun.
The reason for the change in the sun's declination and thus for the existence of the tropics is the inclination of the earth's axis relative to the plane of the earth's orbit, the so-called inclination of the ecliptic of 23 ° 26'05 "(as of May 15, 2017).
Shifting the tropics
Since the inclination of the ecliptic changes in the long term due to perturbations of other bodies in the solar system, the position of the tropics also changes. At the moment they are moving - apart from the short-term tumbling of the earth's axis, the nutation - at an average speed of about one arc minute in 128 years towards the earth's equator, that is about 14.4 m per year. It is assumed, however, that since the formation of the moon, the skew remained all in all about the current order of magnitude.
Tropic of Capricorn
The tropic is the northernmost parallel at which the midday sun just reaches its zenith , namely at the time of the summer solstice in the northern hemisphere around June 21. It is the parallel of 23 ° 26 ′ 04 ″ north latitude (as of June 21, 2015).
The northern tropic is also called the "Tropic of Cancer " ( Latin tropicus cancri , English Tropic of Cancer ) - in the sense of the tropical zodiac signs of antiquity : the constellation that the sun crossed at the solstice was until 15 BC. The constellation Cancer. Because the equinoxes in the sidereal reference system are slowly shifting due to the precession of the earth's axis , this point then moved to the constellation Gemini and has been in the constellation Taurus since 1990 .
Course of the Tropic of Capricorn
The Tropic of Capricorn runs through the Sahara (from the prime meridian to the east) in Algeria , Libya and Egypt . It then runs through the Arabian Peninsula , the Arabian Sea , India , Bangladesh , Myanmar , southern China and Taiwan . In the Pacific, it runs 136 km north of the Hawaiian island of Kaua'i . The tropic crosses Mexico , the Gulf of Mexico and the Atlantic Ocean until it re-enters Africa and the Sahara Desert.
Relevance to international law
The northern tropic limits NATO's sphere of activity to the islands in the North Atlantic belonging to the territorial sovereignty of NATO allies to the south.
"For the purposes of Article 5, an armed attack on one or more parties is any armed attack on [...] the territorial sovereignty of an island in the North Atlantic area north of the Tropic of Cancer."
Tropic of Capricorn
The tropic is the southernmost parallel at which the midday sun just reaches its zenith , namely only on December 21 or 22, the day of the summer solstice in the southern hemisphere (in Europe: winter solstice). It is the parallel of 23 ° 26 ′ 5 ″ south latitude (as of December 21/22, 2014).
In the sense of the tropical signs of the zodiac or also after the constellation of the ecliptic , in which the sun was at the solstice when the constellations were introduced in antiquity , the southern tropic is also known as the "Tropic of Capricorn " ( Latin tropicus capricorni , English Tropic of Capricorn ) . Currently the sun is at the solstice due to the precession in the constellation Sagittarius .
Marking the Tropic of Capricorn on the Stuart Highway in Australia
Marking of the tropic at Itaí in Brazil
Course of the southern tropic
The Tropic of Capricorn runs through (from the prime meridian eastwards) South Africa ( Namibia , Botswana , South Africa , Mozambique , Madagascar ), the Indian Ocean , Australia , the Pacific , South America ( Chile , the northernmost tip of Argentina , Paraguay , Brazil ) and finally the South Atlantic .
| State, territory, sea | additional |
|---|---|
| Atlantic | |
 Namibia
|
Regions: Erongo , Khomas , Hardap and Omaheke |
 Botswana
|
Districts: Kgalagadi , Kweneng and Central |
 South Africa
|
Limpopo Province |
 Mozambique
|
Provinces: Gaza and Inhambane |
| Indian Ocean | Strait of Mozambique |
 Madagascar
|
Provinces: Toliara and Fianarantsoa |
| Indian Ocean | |
 Australia
|
Western Australia, Northern Territory and Queensland |
| Coral sea | Crosses the Cato Reef, in Australia's Coral Sea Islands Territory |
| Pacific | North of the Minerva Reefs (belonging to Tonga) and south of Tubuai (belonging to French Polynesia) |
 Chile
|
Antofagasta region |
 Argentina
|
Provinces: Jujuy , Salta and Formosa |
 Paraguay
|
Departments: Boquerón , Presidente Hayes , Concepción , San Pedro and Amambay |
 Brazil
|
States of Mato Grosso do Sul , Paraná and São Paulo |
| Atlantic |
Countries south of the Tropic of Capricorn
The countries completely south of the Tropic of Capricorn include:
See also
- Polar circle
- Tropic of Cancer (novel by Henry Miller)
- Tropic of Capricorn (novel by Henry Miller)
- Tropic desert
Web links
Individual evidence
- ↑ World map with longitude and latitude (PDF)
- ^ JPL ephemeris
- ↑ Gongjie Li, Konstantin Batygin: Pre-LHB Evolution of the Earth's Obliquity . arxiv : 1409.2881
- ^ Tropic of Cancer Marker. East Rift Valley Scenic Area, accessed January 21, 2018 .
- ↑ The Tokelau and Niue , which belong to New Zealand and the freely associated Cook Islands , are, however, above the Tropic of Capricorn.