equator
The equator of a planet or other ellipsoid of rotation celestial body is the great circle assumed on its surface , on whose plane (the equatorial plane ) the axis of rotation is perpendicular. The earth's surface is divided by the equator into a north and a south half , which is where the Latin name "Gleichmacher" (old: "Equal") comes from. It is the reference circle for the parallel small circles that are used to dimension the earth in north-south direction with the help of circles of latitude . He himself has the geographical latitude 0 °.
The intersection of the equatorial plane of the earth with the celestial sphere around the earth is the celestial equator .
In geometry , the term equator is generally applied to the sphere in connection with an axis defined by its center .
Earth equator
Length and diameter of the equator
The circumference of the equator is 40,075.017 kilometers ( WGS 84 ). In the circular plane of the equator, the earth has a mean diameter of 12,756.274 kilometers.
The length of one nautical mile was originally the equatorial arc over a minute of arc and was 1.853 kilometers in relation to an average earth radius of 6370 kilometers.
States, islands and cities on the equator
The equator crosses the continents Africa , Asia ( Indonesia ) and America ( South America ) as well as the three oceans Atlantic , Pacific and Indian Ocean . It reaches its highest point at over 4500 meters on the southern flank of the Cayambe volcano in Ecuador. Due to the retreat of the glacier , the point has been free of ice since around 2006 - before that, it was the only place on the equator to be covered with snow all year round.
The continental states crossed are:
- Africa
- South America
Island states with one or more islands on the equator are:
- São Tomé and Príncipe (west of Africa)
- Indonesia
Island states with islands on both sides of the equator are the Maldives in the Indian Ocean and Kiribati in the Pacific Ocean .
The following capitals are approximately on the equator:
- São Tomé (35 km north) from São Tomé and Príncipe
- Libreville (40 km north) of Gabon
- Nairobi (141 km south) of Kenya
- Kampala (35 km north) of Uganda
- Quito (20 km south) from Ecuador
- Yaren (50 km south) from Nauru
Directly crossed by the equator:
- the city of Macapá (Brazil)
- the cities of Calacalí , La Concordia and San Antonio de Pichincha in Ecuador
- the city of Pontianak (Indonesia)
- the cities of Maseno , Nanyuki and Nyahururu in Kenya
- the city of Makoua in the Republic of the Congo
- the mountain range of the Cayambe volcano in Ecuador - until 2006 the only section of the equator on which there was snow all year round
- the mountain range of the Wolf Volcano in the Galapagos Islands
- of Lake George and the north coast of Lake Victoria in Uganda
- the Rolas Island near São Tomé and Príncipe
- the UNHCR refugee camp Hagadera near Dadaab (Kenya)
Because of the slight periodic movements of the earth's axis, the current equator can be up to ten meters away from the central equator.
Germany is 47.4 ° to 55.0 ° (about 5300 to 6100 km) from the equator, Austria 46.4 ° to 49.1 °, Switzerland 45.8 ° to 47.8 ° and South Tyrol 46.2 ° to 47.1 °.
Equator in names of states and provinces
Two states refer to the equator in their names: Ecuador and Equatorial Guinea .
After 1801 there was France Equatorial in South America for a short time ( Equatorial France , southern expansion of French Guiana), until 1958 there was also the colony of French Equatorial Africa .
Equatoria has been used several times in history to refer to provinces or states in what is now South Sudan . In South Sudan, three federal states have Equatoria in their name ( Central Equatoria , Eastern Equatoria and Western Equatoria ).
To this day, Equateur is the name of a province in the Congo.
Climate at the equator
On both sides of the equator, there is the climate of the tropics . Due to the high position of the sun at the equator all year round, the irradiation is high and almost constant. The consequences are an almost constant cloud formation and a correspondingly constant level of precipitation. Characteristic of the so-called equatorial climate is a year-round mildness; Seasons like summer or winter z. B. in European standards do not occur. However, near the high mountains, foehn winds on the leeward side can cause longer dry periods.
Others
In addition to the geographic equator, there is the magnetic equator, which is determined by the earth's magnetic poles, and the climatological thermal equator .
A ritual common in seafaring when crossing the equator for the first time is the equator baptism .
"Equator Hike"
In the course of geological time , the spatial position of the earth's body changes relative to its axis of rotation. As a result, the geographic poles "migrate" on the earth's surface and with them the equatorial plane and thus the earth's equator. Two large polar movements of more than 50 ° there and back probably occurred about 800 million years ago.
Equator in the figurative sense
The term equator jokingly stands for an imaginary boundary line. So called
- the white sausage equator the border between old Bavaria and the rest of Germany including the Franconia, which belongs to the Free State of Bavaria,
- the furnace equator is a border in China , north of which is heated in winter (approximately at the level of Shanghai ),
- the Aldi equator is the border between the German areas in which the food chains Aldi-Nord and Aldi-Süd are widespread
- and the beer equator, the border between two regions in which a certain type of beer is preferred, for example Kölsch in the region around Cologne and Altbier in the region bordering to the north around Düsseldorf .
literature
- Joachim Herrmann : dtv atlas astronomy . Dtv, March 2005. ISBN 3-423-03267-7
Web links
Individual evidence
- ↑ The fact that many planets are not exactly a sphere because of their mountains and valleys and also over the oceans and thus their equator is not exactly a circle is neglected. Apart from that, planets are clearly ellipsoids of revolution flattened at the poles .
- ↑ The equatorial climate. www.klima-der-erde.de (private website)
- ^ Adam C. Maloof, Galen P. Halverson, Joseph L. Kirschvink, Daniel P. Schrag, Benjamin P. Weiss, Paul F. Hoffman: Combined paleomagnetic, isotopic, and stratigraphic evidence for true polar wander from the Neoproterozoic Akademikerbreen Group, Svalbard , Norway. Geological Society of America Bulletin. Vol. 188, No. 9-10, 2006, pp. 1099-2014, doi : 10.1130 / B25892.1 (alternative full-text access : Princeton University ).