# equator

Model of the earth with equator (red), parallel circles of latitude and meridians starting from the poles

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 equator on a world map in the middle between the Arctic (in the north, above) and Antarctica (in the south, below).

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:

Island states with one or more islands on the equator are:

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:

Directly crossed by the equator:

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 °.

Older equatorial monument (around 1980) near Quito , about 240 m south of the equator
New equator monument in Ecuador (2007) on the Panamericana (background: Cayambe volcano )

### 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

Equator, 31 ° 45 'w. L.

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 .