Equator

World map showing the equator in red

The equator is an imaginary circle drawn around a planet (or other astronomical object) at a distance halfway between the poles. The equator divides the planet into a Northern Hemisphere and a Southern Hemisphere. The latitude of the equator is, by definition, 0°. The length of Earth's equator is about 40,075.0 km, or 24,901.5 miles.

The equator is one of the five main circles of latitude based on the relationship of the Earth's rotation and plane of orbit around the sun. Additionally, the equator is the only line of latitude which is also a great circle.

The Sun, in its seasonal movement through the sky, passes directly over the equator twice each year on the March and September Equinoxes. At the equator, the rays of the sun are perpendicular to the surface of the earth on these dates.

Places near the equator experience the quickest rates of sunrise and sunset in the world, taking minutes. Such places also have a relatively constant amount of day/night time on every day throughout the year compared with more northerly or southerly places.

In tourist areas, the equator is often marked on the sides of roads

Also, in relation to launching of satellites, the closeness of the launch centre requires the thrust to be comparatively lesser, and as one moves away from the equator, one has to ensure that the payload in the launch vehicle is not much, for to get into the right orbit, more thrust is required.

Equatorial climate

In many tropical regions people identify 2 seasons, wet and dry, but most places very close to the equator are wet throughout the year, although seasons can vary depending on a variety of factors including elevation and proximity to an ocean.

The surface of the Earth at the equator is mainly ocean.

The highest point on the Equator is 4,690 m, at 77°59′31" W on the south slopes of Volcán Cayambe (summit 5,790 m) in Ecuador. This is a short distance above the snow line, and is the only point on the Equator where snow lies on the ground (Google Earth satellite data and photos).

Equatorial countries

The equator traverses the land and/or water of 13 countries in total:
* São Tomé and Príncipe - passing through Ilhéu das Rolas, an islet in this archipelago
* Gabon
* Republic of the Congo
* Democratic Republic of Congo
* Uganda - including some islets in Lake Victoria
* Kenya
* Somalia
* Maldives - misses every island, passing between Gaafu Dhaalu Atoll and Gnaviyani Atoll
* Indonesia - crosses many islands, most notably Sumatra, Borneo, Sulawesi, and Halmahera
* Kiribati - misses every island, passing between Aranuka and Nonouti Atolls in the Gilbert Islands
* Ecuador - including Isabela Island in the Galápagos Islands
* Colombia
* Brazil - including some islands in the mouth of the Amazon River and passing through Macapá, capital of Amapá state

The equator narrowly misses the territory of the United States near Baker Island and Jarvis Island in the United States Minor Outlying Islands. The southern end of Baker Island lies just 13 minutes of latitude north of the equator, putting the equator just outside the 12-mile limit for territorial waters. However, the equator does pass through the Contiguous Waters and the Exclusive Economic Zone of the United States.

Contrary to its name, no part of Equatorial Guinea lies on the equator.

"Crossing the Line"

Seafaring tradition maintains that all sailors who cross the equator during a nautical voyage must undergo rites of passage and elaborate rituals initiating them into The Solemn Mysteries of the Ancient Order of the Deep. These rituals date back to the Middle Ages, though the current ceremonies are most likely derived from Viking traditions. Those who have never "crossed the line" are derisively referred to as "pollywogs" or simply "slimy wogs". Upon entering the domain of His Royal Majesty, Neptunus Rex, all wogs are subject to various initiation rituals performed by those members of the crew who have made the journey before. Upon completion of the initiation ceremony, the wogs are then known as "trusty Shellbacks". If the crossing of the equator is done at the 180th meridian, the title of "Golden Shellback" is conferred, recognizing the simultaneous entry into the realm of the Golden Dragon. If the crossing occurs at the Greenwich or Prime Meridian, the sailor is considered to be an "Emerald Shellback".

See also

* Thermal equator
* Intertropical Convergence Zone
* Prime Meridian