An equator is the intersection of the surface of a rotating sphere
(such as a planet) with the plane perpendicular to the axis of
rotation and midway between its poles.
On Earth, the
Equator

Equator is an imaginary line on the surface, equidistant
from the North and South Poles, dividing the
Earth

Earth into Northern and
Southern Hemispheres. It is about 40,075 kilometres (24,901 mi)
long, of which 78.7% lies across water and 21.3% over land.
Contents
1 Overview
2 Geodesy
2.1 Precise location
2.2 Exact length
3 Crossing-the-
Equator

Equator ceremonies
4 Equatorial countries and territories
5 Equatorial seasons and climate
6 See also
7 References
8 Sources
Overview[edit]
Left: A monument marking the
Equator

Equator near the town of Pontianak,
Indonesia
Right: Road sign marking the
Equator

Equator near Nanyuki, Kenya
The latitude of the Earth's equator is, by definition, 0° (zero
degrees) of arc. The
Equator

Equator is one of the five notable circles of
latitude on Earth; the other four are the two Polar Circles (the
Arctic Circle

Arctic Circle and the Antarctic Circle) and the two Tropical Circles
(the
Tropic of Cancer

Tropic of Cancer and the Tropic of Capricorn). The
Equator

Equator is the
only line of latitude which is also a great circle — that is, one
whose plane passes through the center of the globe. The plane of
Earth's equator, when projected outwards to the celestial sphere,
defines the celestial equator.
In the cycle of Earth's seasons, the plane of the equator passes
through the
Sun

Sun twice per year: at the March and September equinoxes.
To a person on the Earth, the
Sun

Sun appears to travel North or South
over the
Equator

Equator (or the celestial equator) at these times. Light rays
from the center of the
Sun

Sun are perpendicular to the surface of the
Earth

Earth at the point of solar noon on the Equator.
The
Equator

Equator marked as it crosses Ilhéu das Rolas, in São Tomé and
Príncipe
The Marco Zero monument marking the
Equator

Equator in Macapá, Brazil.
Locations on the
Equator

Equator experience the quickest sunrises and sunsets,
because the sun moves nearly perpendicular to the horizon for most of
the year. The length of daylight (sunrise to sunset) is almost
constant throughout the year; it is about fourteen minutes longer than
nighttime due to atmospheric refraction and the fact that sunrise is
begun (or sunset is ended) as the upper edge, not the center, of the
Sun's disk crosses the horizon.
The
Earth

Earth bulges slightly at the Equator; the "average" diameter of
the
Earth

Earth is 12,750 kilometres (7,922 mi), but the diameter at
the
Equator

Equator is about 43 kilometres (27 mi) greater than at the
poles.[1]
Sites near the Equator, such as the
Guiana Space Centre

Guiana Space Centre in Kourou,
French Guiana, are good locations for spaceports as they have a faster
rotational speed than other latitudes; the added velocity reduces the
fuel needed to launch spacecraft. Because the
Earth

Earth spins to the east,
spacecraft must also launch to the east (or to the southeast or
northeast) to take advantage of this Earth-boost of speed.[citation
needed]
Geodesy[edit]
Further information:
Earth

Earth ellipsoid and Reference ellipsoid
Precise location[edit]
The precise location of the
Equator

Equator is not truly fixed; the true
equatorial plane is perpendicular to the Earth's spin axis, which
drifts about 9 metres (30 ft) during a year. This effect must be
accounted for in detailed geophysical measurements.[citation needed]
Exact length[edit]
In two widely used geodetic standards, the
Equator

Equator is modelled as a
circle whose radius is a whole number of metres. In 1976 the IAU chose
a radius of 6,378.140 kilometres (3,963.192 mi) (codified as the
IAU-1976 value), later refined by the IUGG to 6,378.137 kilometres
(3,963.191 mi) and adopted in WGS-84. Despite this change, the
yet more recent IAU-2000 retained the old IAU-1976 value. If it were
really circular, the length of the
Equator

Equator would be exactly 2π times
the radius, namely 40,075.036 kilometres (24,901.473 mi).
However, due to the effect of the tides on the Earth's surface the
actual circumference at the equator is about 40,075.16 kilometres
(24,901.55 mi).
The geographical mile is defined as one arc minute of the Equator, so
it has different values depending on which radius is assumed. For
example, by WSG-84, the distance is 1,855.3248 metres
(6,087.024 ft), while by IAU-2000, it is 1,855.3257 metres
(6,087.027 ft). This is a difference of less than one millimeter
over the total distance (approximately 1.86 kilometres
(1.16 mi)).
The earth is commonly modeled as a sphere flattened 0.336% along its
axis. This makes the
Equator

Equator 0.16% longer than a meridian (a great
circle passing through the two poles). The IUGG standard meridian is,
to the nearest millimetre, 40,007.862917 kilometres
(24,859.733480 mi), one arc minute of which is 1,852.216 metres
(6,076.82 ft), explaining the SI standardization of the nautical
mile as 1,852 metres (6,076 ft), more than 3 metres (9.8 ft)
less than the geographical mile.
The sea-level surface of the
Earth

Earth (the geoid) is irregular, so the
actual length of the
Equator

Equator is not so easy to determine. Aviation
Week and Space Technology on 9 October 1961 reported that measurements
using the Transit IV-A satellite had shown the equatorial "diameter"
from longitude 11° West to 169° East to be 1,000 feet (300 m)
greater than its "diameter" ninety degrees away.[citation needed]
Crossing-the-
Equator

Equator ceremonies[edit]
Main article: Line-crossing ceremony
Certain navies, such as the Royal Navy, Russian Navy, and US Navy,
have a tradition of holding ceremonies aboard ships to mark sailors'
first crossing of the Equator. These ceremonial events have in the
past been notorious for their brutality.[citation needed] Milder
line-crossing ceremonies, typically featuring King Neptune, are also
held for passengers' entertainment on some civilian ocean liners and
cruise ships.[citation needed]
Equatorial countries and territories[edit]
Map all coordinates using: OpenStreetMap · Google Maps
Download coordinates as: KML · GPX
The
Equator

Equator passes through the land of 11 countries. Starting at the
Prime Meridian

Prime Meridian and heading eastwards, the
Equator

Equator passes through:
Co-ordinates
Country, territory or sea
Notes
0°N 0°E / 0°N 0°E / 0; 0 (Prime Meridian)
Atlantic Ocean
Gulf of Guinea
0°0′N 6°31′E / 0.000°N 6.517°E / 0.000; 6.517
(São Tomé and Príncipe)
São Tomé and Príncipe
Ilhéu das Rolas
0°0′N 9°21′E / 0.000°N 9.350°E / 0.000; 9.350
(Gabon)
Gabon
passes 8.9 km (5.5 mi) south of Ayem, 10.6 km
(6.6 mi) north of Mayene, Booue
0°0′N 13°56′E / 0.000°N 13.933°E / 0.000; 13.933
(Republic of the Congo)
Republic of the Congo
Passing through the town of Makoua.
0°0′N 17°46′E / 0.000°N 17.767°E / 0.000; 17.767
(Democratic Republic of the Congo)
Democratic Republic of the Congo
Passing 9 km (5.6 mi) south of central Butembo
0°0′N 29°43′E / 0.000°N 29.717°E / 0.000; 29.717
(Uganda)
Uganda
Passing 32 km (20 mi) south of central Kampala
0°0′N 32°22′E / 0.000°N 32.367°E / 0.000; 32.367
(Lake Victoria)
Lake Victoria
Passing through some islands of Uganda
0°0′N 34°0′E / 0.000°N 34.000°E / 0.000; 34.000
(Kenya)
Kenya
Passing 6 km (3.7 mi) north of central Kisumu
0°0′N 41°0′E / 0.000°N 41.000°E / 0.000; 41.000
(Somalia)
Somalia
0°0′N 42°53′E / 0.000°N 42.883°E / 0.000; 42.883
(Indian Ocean)
Indian Ocean
Passing between
Huvadhu Atoll

Huvadhu Atoll and
Fuvahmulah

Fuvahmulah of the Maldives
0°0′N 98°12′E / 0.000°N 98.200°E / 0.000; 98.200
(Indonesia)
Indonesia
The Batu Islands,
Sumatra

Sumatra and the Lingga Islands
0°0′N 104°34′E / 0.000°N 104.567°E / 0.000;
104.567 (Karimata Strait)
Karimata Strait
0°0′N 109°9′E / 0.000°N 109.150°E / 0.000; 109.150
(Indonesia)
Indonesia
Borneo
0°0′N 117°30′E / 0.000°N 117.500°E / 0.000;
117.500 (Makassar Strait)
Makassar Strait
0°0′N 119°40′E / 0.000°N 119.667°E / 0.000;
119.667 (Indonesia)
Indonesia
Sulawesi

Sulawesi (Celebes)
0°0′N 120°5′E / 0.000°N 120.083°E / 0.000; 120.083
(Gulf of Tomini)
Gulf of Tomini
0°0′N 124°0′E / 0.000°N 124.000°E / 0.000; 124.000
(Molucca Sea)
Molucca Sea
0°0′N 127°24′E / 0.000°N 127.400°E / 0.000;
127.400 (Indonesia)
Indonesia
Kayoa and
Halmahera

Halmahera islands
0°0′N 127°53′E / 0.000°N 127.883°E / 0.000;
127.883 (
Halmahera

Halmahera Sea)
Halmahera

Halmahera Sea
0°0′N 129°20′E / 0.000°N 129.333°E / 0.000;
129.333 (Indonesia)
Indonesia
Gebe and Kawe islands
0°0′N 129°21′E / 0.000°N 129.350°E / 0.000;
129.350 (Pacific Ocean)
Pacific Ocean
Passing between
Aranuka

Aranuka and
Nonouti

Nonouti atolls,
Kiribati

Kiribati (at
0°0′N 173°40′E / 0.000°N 173.667°E / 0.000; 173.667)
0°0′N 80°6′W / 0.000°N 80.100°W / 0.000; -80.100
(Ecuador)
Ecuador
Passing 24 km (15 mi) north of central Quito, near Mitad del
Mundo, and precisely at the location of Catequilla, a pre-Columbian
ruin
Also, Isabela Island in the Galápagos Islands
0°0′N 75°32′W / 0.000°N 75.533°W / 0.000; -75.533
(Colombia)
Colombia
Passing 4.3 km (2.7 mi) north of the border with Peru
0°0′N 70°3′W / 0.000°N 70.050°W / 0.000; -70.050
(Brazil)
Brazil
Amazonas
Roraima
Pará
Amapá

Amapá (passing slightly south of the city center of the state capital
Macapá)
0°0′N 49°21′W / 0.000°N 49.350°W / 0.000; -49.350
(Atlantic Ocean)
Atlantic Ocean
At the Perigoso Canal on the mouth of the Amazon River
Despite its name, no part of
Equatorial Guinea

Equatorial Guinea lies on the Equator.
However, its island of Annobón is 155 km (96 mi) south of
the Equator, and the rest of the country lies to the north.
GPS reading taken on the
Equator

Equator close to the Quitsato Sundial, at
Mitad del Mundo, Ecuador.[2]
Equatorial seasons and climate[edit]
Main articles: Seasons, Tropics, and Effect of sun angle on climate
Diagram of the seasons, depicting the situation at the December
solstice. Regardless of the time of day (i.e. the Earth’s rotation
on its axis), the
North Pole

North Pole will be dark, and the
South Pole

South Pole will be
illuminated; see also arctic winter. In addition to the density of
incident light, the dissipation of light in the atmosphere is greater
when it falls at a shallow angle.
Seasons

Seasons result from the tilt of the Earth's axis compared to the plane
of its revolution around the Sun. Throughout the year the northern and
southern hemispheres are alternately turned either toward or away from
the sun depending on Earth's position in its orbit. The hemisphere
turned toward the sun receives more sunlight and is in summer, while
the other hemisphere receives less sun and is in winter (see
solstice).
At the equinoxes, the Earth's axis is perpendicular to the sun rather
than tilted toward or away, meaning that day and night are both about
12 hours long across the whole of the Earth.
The
Equator

Equator lies mostly on the three largest oceans: the Atlantic
Ocean, the Indian Ocean, and the Pacific Ocean. Near the
Equator

Equator there
is little temperature change throughout the year, though there may be
dramatic differences in rainfall and humidity. The terms summer,
autumn, winter and spring do not generally apply. Lowlands around the
Equator

Equator generally have a tropical rainforest climate, also known as an
equatorial climate, though cold currents cause some regions to have
tropical monsoon climates with a dry season in the middle of the year,
and the
Somali Current

Somali Current generated by the Asian monsoon due to
continental heating via the high
Tibetan Plateau

Tibetan Plateau causes Greater
Somalia

Somalia to have an arid climate despite its equatorial location.
Average annual temperatures in equatorial lowlands are around
31 °C (88 °F) during the afternoon and 23 °C
(73 °F) around sunrise. Rainfall is away from cold current
upwelling zones very high, from 2,500 to 3,500 mm (98 to
138 in) per year. There are about 200 rainy days per year and
average annual sunshine hours are around 2,000. Despite high
year-round sea level temperatures, some higher altitudes such as the
Andes

Andes and
Mount Kilimanjaro

Mount Kilimanjaro have glaciers. The highest point on the
Equator

Equator is at the elevation of 4,690 metres (15,387 ft), at
0°0′0″N 77°59′31″W / 0.00000°N 77.99194°W /
0.00000; -77.99194 (highest point on the Equator), found on the
southern slopes of
Volcán Cayambe

Volcán Cayambe [summit 5,790 metres
(18,996 ft)] in Ecuador. This is slightly above the snow line and
is the only place on the
Equator

Equator where snow lies on the ground. At the
Equator

Equator the snow line is around 1,000 metres (3,280 ft) lower
than on
Mount Everest

Mount Everest and as much as 2,000 metres (6,560 ft)
lower than the highest snow line in the world, near the Tropic of
Capricorn on Llullaillaco.
Climate data for Macapá,
Brazil

Brazil in South America
Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Year
Average high °C (°F)
29.7
(85.5)
29.2
(84.6)
29.3
(84.7)
29.5
(85.1)
30.0
(86)
30.3
(86.5)
30.6
(87.1)
31.5
(88.7)
32.1
(89.8)
32.6
(90.7)
32.3
(90.1)
31.4
(88.5)
30.71
(87.28)
Daily mean °C (°F)
26.4
(79.5)
26.2
(79.2)
26.3
(79.3)
26.5
(79.7)
26.8
(80.2)
26.8
(80.2)
26.8
(80.2)
27.4
(81.3)
27.8
(82)
28.1
(82.6)
27.9
(82.2)
27.4
(81.3)
27.03
(80.65)
Average low °C (°F)
23.0
(73.4)
23.1
(73.6)
23.2
(73.8)
23.5
(74.3)
23.5
(74.3)
23.2
(73.8)
22.9
(73.2)
23.3
(73.9)
23.4
(74.1)
23.5
(74.3)
23.5
(74.3)
23.4
(74.1)
23.29
(73.92)
Average rainfall mm (inches)
299.6
(11.795)
347.0
(13.661)
407.2
(16.031)
384.3
(15.13)
351.5
(13.839)
220.1
(8.665)
184.8
(7.276)
98.00
(3.8583)
42.60
(1.6772)
35.50
(1.3976)
58.40
(2.2992)
142.5
(5.61)
2,571.5
(101.2393)
Average rainy days (≥ 0.1 mm)
23
22
24
24
25
22
19
13
6
5
6
14
203
Mean monthly sunshine hours
148.8
113.1
108.5
114.0
151.9
189.0
226.3
272.8
273.0
282.1
252.0
204.6
2,336.1
Source:
World Meteorological Organization

World Meteorological Organization (UN),[3] Hong Kong
Observatory[4]
Climate data for
Pontianak, Indonesia

Pontianak, Indonesia in Asia
Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Year
Average high °C (°F)
32.4
(90.3)
32.7
(90.9)
32.9
(91.2)
33.2
(91.8)
33.0
(91.4)
33.2
(91.8)
32.9
(91.2)
33.4
(92.1)
32.6
(90.7)
32.6
(90.7)
32.2
(90)
32.0
(89.6)
32.7
(90.9)
Daily mean °C (°F)
27.6
(81.7)
27.7
(81.9)
28.0
(82.4)
28.2
(82.8)
28.2
(82.8)
28.2
(82.8)
27.7
(81.9)
27.9
(82.2)
27.6
(81.7)
27.7
(81.9)
27.4
(81.3)
27.2
(81)
27.7
(81.9)
Average low °C (°F)
22.7
(72.9)
22.6
(72.7)
23.0
(73.4)
23.2
(73.8)
23.4
(74.1)
23.1
(73.6)
22.5
(72.5)
22.3
(72.1)
22.6
(72.7)
22.8
(73)
22.6
(72.7)
22.4
(72.3)
22.7
(72.9)
Average rainfall mm (inches)
260
(10.24)
215
(8.46)
254
(10)
292
(11.5)
256
(10.08)
212
(8.35)
201
(7.91)
180
(7.09)
295
(11.61)
329
(12.95)
400
(15.75)
302
(11.89)
3,196
(125.83)
Average rainy days (≥ 0.1 mm)
15
13
21
22
20
18
16
25
14
27
25
22
238
Source:
World Meteorological Organization

World Meteorological Organization (UN)[5]
Climate data for Libreville,
Gabon

Gabon in Africa
Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Year
Average high °C (°F)
29.5
(85.1)
30.0
(86)
30.2
(86.4)
30.1
(86.2)
29.4
(84.9)
27.6
(81.7)
26.4
(79.5)
26.8
(80.2)
27.5
(81.5)
28.0
(82.4)
28.4
(83.1)
29.0
(84.2)
28.58
(83.44)
Daily mean °C (°F)
26.8
(80.2)
27.0
(80.6)
27.1
(80.8)
26.6
(79.9)
26.7
(80.1)
25.4
(77.7)
24.3
(75.7)
24.3
(75.7)
25.4
(77.7)
25.7
(78.3)
25.9
(78.6)
26.2
(79.2)
25.95
(78.71)
Average low °C (°F)
24.1
(75.4)
24.0
(75.2)
23.9
(75)
23.1
(73.6)
24.0
(75.2)
23.2
(73.8)
22.1
(71.8)
21.8
(71.2)
23.2
(73.8)
23.4
(74.1)
23.4
(74.1)
23.4
(74.1)
23.30
(73.94)
Average rainfall mm (inches)
250.3
(9.854)
243.1
(9.571)
363.2
(14.299)
339.0
(13.346)
247.3
(9.736)
54.10
(2.1299)
6.600
(0.25984)
13.70
(0.5394)
104.0
(4.094)
427.2
(16.819)
490.0
(19.291)
303.2
(11.937)
2,841.7
(111.87614)
Average rainy days (≥ 0.1 mm)
17.9
14.8
19.5
19.2
16.0
3.70
1.70
4.90
14.5
25.0
22.6
17.6
177.4
Mean monthly sunshine hours
176.7
182.7
176.7
177.0
158.1
132.0
117.8
89.90
96.00
111.6
135.0
167.4
1,720.9
Source:
World Meteorological Organization

World Meteorological Organization (UN),[6] Hong Kong
Observatory[7]
See also[edit]
Geography portal
1st parallel north
1st parallel south
Antarctic Circle
Arctic Circle
Coriolis effect
Intertropical Convergence Zone
Prime Meridian
Thermal equator
Tropic of Cancer
Tropic of Capricorn
References[edit]
^ "Equator". National Geographic - Education. Retrieved 29 May
2013.
^ Instituto Geográfico Militar de
Ecuador

Ecuador (24 January 2005). "Memoria
Técnica de la Determinación de la Latitud Cero" (in Spanish).
^ "Weather Information for Macapa".
^ Climatological Information for Macapa,
Brazil

Brazil - Hong Kong
Observatory
^ "Weather Information for Pontianak".
^ "Weather Information for Libreville".
^ Climatological Information for Libreville,
Gabon

Gabon - Hong Kong
Observatory
Sources[edit]
Wikimedia Commons has media related to Equator.
Moritz, H (September 1980). "Geodetic Reference System 1980". Bulletin
Géodésique. Berlin: Springer-Verlag. 54 (3): 395–405.
Bibcode:1980BGeod..54..395M. doi:10.1007/BF02521480.
(IUGG/WGS-84 data)
Taff, Laurence G (1981). Computational Spherical Astronomy. New York:
Wiley. ISBN 0-471-06257-X. OCLC 6532537. (IAU data)
v
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Circles of latitude / meridians
Equator
Tropic of Cancer
Tropic of Capricorn
Arctic Circle
Antarctic Circle
Equator
Tropic of Cancer
Tropic of Capricorn
Arctic Circle
Antarctic Circle
Equator
Tropic of Cancer
Tropic of Capricorn
Arctic Circle
Antarctic Circle
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