View source for Astronomy:Equator

{{Short description|Circle of latitude}}
{{Location map-line|lat=0|caption=Equator in the map of Earth}}

[[File:Equator and Prime Meridian.svg|thumb|upright=1.35|Countries and territories that touch the equator (red) or the [[Earth:Prime meridian|prime meridian]] (blue)]]

The [[Astronomy:Earth|Earth]]'s '''equator''' is an imaginary planetary line that is about {{cvt|40,075|km|mi}} long in circumference. The equator divides the planet into the [[Earth:Northern Hemisphere|Northern Hemisphere]] and [[Earth:Southern Hemisphere|Southern Hemisphere]] and is located at 0 degrees [[Earth:Latitude|latitude]], the halfway line between the [[Earth:North Pole|North Pole]] and [[Earth:South Pole|South Pole]].<ref name="National">{{cite web |url=https://www.nationalgeographic.org/encyclopedia/equator/|title=Equator|website=National Geographic - Education|access-date= 9 March 2021}}</ref>

In [[Three-dimensional space|spatial (3D)]] [[Geometry|geometry]], as applied in [[Astronomy:Astronomy|astronomy]], the '''equator''' of a rotating [[Spheroid|spheroid]] (such as a [[Astronomy:Planet|planet]]) is the parallel (circle of latitude) at which latitude is defined to be 0°. It is the [[Earth:Imaginary line|imaginary line]] on the spheroid, equidistant from its [[Earth:Geographical pole|poles]], dividing it into northern and southern hemispheres. In other words, it is the intersection of the spheroid with the [[Plane (mathematics)|plane]] [[Perpendicular|perpendicular]] to its axis of [[Physics:Rotation|rotation]] and midway between its [[Earth:Geographical pole|geographical pole]]s.

When the [[Astronomy:Sun|Sun]] is directly above the  Earth's equator (on the [[Astronomy:Equinox|equinox]]es of approximately March 20 and September 23), [[Astronomy:Sunlight|sunlight]] shines perpendicular to the Earth's axis of rotation, and all latitudes have a 12-hour day and 12-hour night. On and near the equator sunlight comes from almost directly above every day year-round, and thus the equator has a rather stable daytime temperature the whole year.

==Etymology==
The name is derived from [[Social:Medieval Latin|medieval Latin]] word {{lang|la|aequator}}, in the phrase {{lang|la|circulus aequator diei et noctis}}, meaning 'circle '''equalizing''' day and night', from the [[Social:Latin|Latin]] word {{lang|la|aequare}} meaning 'make equal'.<ref>{{Cite web|url=https://en.oxforddictionaries.com/definition/equator|title=Definition of equator|website=OxfordDictionaries.com|access-date=5 May 2018}}</ref>

==Overview==
{{multiple image
| align = right
| image1 = Equator monument.jpg
| width1 = 150
| alt1 = 
| caption1 = 
| image2 = Equator sign kenya.jpg
| width2 = 125
| alt2 = 
| caption2 = 
| footer = ''Left'': A monument marking the equator near the city of Pontianak, Indonesia<br />''Right'': Road sign marking the equator near Nanyuki, Kenya
}}

The [[Earth:Latitude|latitude]] of the Earth's equator is, by definition, 0° (zero [[Degree (angle)|degrees]]) of arc. The equator is one of the five notable circles of latitude on Earth; the other four are both polar circles (the Arctic Circle and the Antarctic Circle) and both tropical circles (the Tropic of Cancer and the Tropic of Capricorn). The equator is the only line of latitude which is also a [[Great circle|great circle]]—that is, one whose [[Plane (mathematics)|plane]] passes through the center of the globe. The plane of Earth's equator, when projected outwards to the [[Celestial sphere|celestial sphere]], defines the [[Celestial equator|celestial equator]].

In the cycle of Earth's [[Physics:Season|season]]s, the equatorial plane runs through the Sun twice per [[Year|year]]: on the [[Astronomy:Equinox|equinox]]es in [[Astronomy:March equinox|March]] and [[Astronomy:September equinox|September]]. To a person on Earth, the Sun [[Astronomy:Subsolar point|appears to travel above]] the equator (or along the celestial equator) at these times. Light rays from the Sun's center are [[Perpendicular|perpendicular]] to Earth's surface at the point of [[Astronomy:Noon#Solar noon|solar noon]] on the equator.

[[File:Equator Sao Tome.jpg|thumb|The equator marked as it crosses Ilhéu das Rolas, in São Tomé and Príncipe]]
[[File:equator Line Monument, Macapá city, Brazil.jpg|thumb|The Marco Zero monument marking the equator in Macapá, {{wipe|Brazil}}]]

Locations on the equator experience the shortest [[Astronomy:Sunrise|sunrise]]s and [[Astronomy:Sunset|sunset]]s because the Sun's [[Astronomy:Sun path|daily path]] is nearly perpendicular to the [[Horizon|horizon]] for most of the year. The length of [[Physics:Daylight|daylight]] (sunrise to sunset) is almost constant throughout the year; it is about 14 minutes longer than nighttime due to [[Astronomy:Atmospheric refraction|atmospheric refraction]] and the fact that sunrise begins (or sunset ends) as the upper limb, not the center, of the Sun's disk contacts the horizon.

Earth [[Astronomy:Equatorial bulge|bulges slightly]] at the equator; the "average" diameter of Earth is {{cvt|12750.|km|mi}}, but the diameter at the equator is about {{cvt|43|km|mi}} greater than at the poles.<ref name="National"></ref>

Sites near the equator, such as the [[Organization:Guiana Space Centre|Guiana Space Centre]] in Kourou, French Guiana, are good locations for spaceports as they have the fastest [[Physics:Rotational speed|rotational speed]] of any latitude, {{cvt|460.|m}}/sec. The added [[Astronomy:Delta-v|velocity]] reduces the fuel needed to launch spacecraft eastward (in the direction of Earth's rotation) to orbit, while simultaneously avoiding costly maneuvers to flatten inclination during missions such as the Apollo moon landings.<ref name="Moonport">{{cite web |author1=William Barnaby Faherty |author2=Charles D. Benson |title=Moonport: A History of Apollo Launch Facilities and Operations |url=http://www.hq.nasa.gov/office/pao/History/SP-4204/contents.html |publisher=NASA Special Publication-4204 in the NASA History Series |access-date=8 May 2019 |archive-url=https://web.archive.org/web/20180915105350/https://www.hq.nasa.gov/office/pao/History/SP-4204/contents.html |archive-date=15 September 2018 |page=Chapter 1.2: A Saturn Launch Site |date=1978 |quote=Equatorial launch sites offered certain advantages over facilities within the continental United States. A launching due east from a site on the equator could take advantage of the earth's maximum rotational velocity ({{cvt|460.|m/s}}) to achieve orbital speed. The more frequent overhead passage of the orbiting vehicle above an equatorial base would facilitate tracking and communications. Most important, an equatorial launch site would avoid the costly dogleg technique, a prerequisite for placing rockets into equatorial orbit from sites such as Cape Canaveral, Florida (28 degrees north latitude). The necessary correction in the space vehicle's trajectory could be very expensive - engineers estimated that doglegging a Saturn vehicle into a low-altitude equatorial orbit from Cape Canaveral used enough extra propellant to reduce the payload by as much as 80%. In higher orbits, the penalty was less severe but still involved at least a 20% loss of payload. |url-status=live }}</ref>

==Geodesy==
{{further|Earth:Earth ellipsoid|Earth:Reference ellipsoid}}

===Precise location===
The precise location of the equator is not truly fixed; the true equatorial plane is perpendicular to the Earth's rotation axis, which [[Astronomy:Polar motion|drifts]] about {{convert|9|m|0}} during a year. This effect must be accounted for in detailed geophysical measurements.{{citation needed|date=April 2017}}

Geological samples show the equator significantly changed positions between 12 and 48&nbsp;million years ago, as sediment deposited by ocean thermal currents at the equator have shifted. The deposits by thermal currents are determined by the axis of the earth, which determines solar coverage of the Earth's surface. Changes in the Earth axis can also be observed in the geographic layout of volcanic island chains, which are created by shifting hot spots under the Earth's crust as the axis and crust move.<ref> https://www.discovermagazine.com/environment/millions-of-years-ago-the-poles-moved-and-it-could-have-triggered-an-ice-age</ref>  This correlates with the Indian plate crashing into Asia as well as the Himalayan uplift.

===Exact length===
{{main|Earth:Earth's circumference}}
The International Association of Geodesy (IAG) and the International Astronomical Union (IAU) use an equatorial radius of {{cvt|6,378.1366|km}} (codified as the IAU 2009 value).<ref>{{cite journal |url= http://www.sai.msu.ru/neb/rw/CelMech110.pdf |title= The IAU 2009 system of astronomical constants: the report of the IAU working group on numerical standards for Fundamental Astronomy |journal= Celest Mech Dyn Astr |date= 2011|volume= 110 |pages= 293–304 |doi= 10.1007/s10569-011-9352-4 |first1= Brian |last1= Luzum |first2= Nicole |last2= Capitaine |first3= Agnès |last3= Fienga |first4= William |last4= Folkner |first5= Toshio |last5= Fukushima |first6= James |last6= Hilton |first7= Catherine |last7= Hohenkerk |first8= George |last8= Krasinsky |first9= Gérard |last9= Petit |first10= Elena |last10= Pitjeva |first11= Michael |last11= Soffel |first12= Patrick |last12= Wallace |issue= 4 |bibcode= 2011CeMDA.110..293L|s2cid= 122755461 |doi-access= free }}</ref> This equatorial radius is also in the 2003 and 2010 IERS Conventions.<ref>{{cite web|url = http://iers-conventions.obspm.fr/2010/2010_official/chapter1/tn36_c1.pdf|title= General definitions and numerical standards|work = IERS Technical Note 36 |archive-url=https://web.archive.org/web/20181218054401/http://iers-conventions.obspm.fr/2010/2010_official/chapter1/tn36_c1.pdf|archive-date = 18 December 2018}}</ref> It is also the equatorial radius used for the IERS 2003 ellipsoid. If it were really circular, the length of the equator would then be exactly 2π times the radius, namely {{cvt|40,075.0142|km}}. The [[Earth:GRS 80|GRS 80]] (Geodetic Reference System 1980) as approved and adopted by the IUGG at its Canberra, Australia meeting of 1979 has an equatorial radius of {{cvt|6,378.137|km}}. The WGS 84 (World Geodetic System 1984) which is a standard for use in cartography, geodesy, and satellite navigation including [[Engineering:Global Positioning System|GPS]], also has an equatorial radius of {{cvt|6,378.137|km}}. For both GRS 80 and WGS 84, this results in a length for the equator of {{cvt|40,075.0167|km}}.

The [[Geographical mile|geographical mile]] is defined as one [[Arc-minute|arc-minute]] of the equator, so it has different values depending on which radius is assumed. For example, by WSG-84, the distance is {{convert|1855.3248|m}}, while by IAU-2000, it is {{convert|1855.3257|m}}. This is a difference of less than {{Convert|1|mm|spell=in}} over the total distance (approximately {{convert|1.86|km||disp=or}}).

The earth is commonly modeled as a [[Sphere|sphere]] flattened 0.336% along its axis. This makes the equator 0.16% longer than a meridian (a great circle passing through the two poles). The IUGG standard meridian is, to the nearest millimetre, {{convert|40007.862917|km}}, one arc-minute of which is {{convert|1852.216|m}}, explaining the [[International System of Units|SI]] standardization of the [[Nautical mile|nautical mile]] as {{convert|1852|m}}, more than {{convert|3|m}} less than the [[Geographical mile|geographical mile]].

The [[Sea level|sea-level]] surface of the Earth (the [[Geoid|geoid]]) is irregular, so the actual length of the equator is not so easy to determine. ''Aviation Week and Space Technology'' on 9 October 1961 reported that measurements using the [[Engineering:Transit (satellite)|Transit]] IV-A satellite had shown the equatorial diameter from longitude 11° West to 169° East to be {{convert|1000.|ft}} greater than its diameter ninety degrees away.{{citation needed|date=March 2012}}

==Equatorial countries and territories==
{{kml}}
[[File:ECSundialGPS.jpg|thumb|upright|GPS reading taken on the equator close to the Quitsato Sundial, in Cayambe, Ecuador<ref name="Informe que determina la posición de la Línea Ecuatorial">{{cite web|author=Instituto Geográfico Militar de Ecuador|title=Memoria Técnica de la Determinación de la Latitud Cero|url=https://www.scribd.com/doc/97475201/Documento-Posicionamiento-Reloj-Solar|date=24 January 2005|language=es}}</ref>]]

The equator passes through the land of 11 countries. Indonesia is the country straddling the greatest length of the equatorial line across both land and sea. Starting at the Prime Meridian and heading eastwards, the equator passes through:
{| class="wikitable plainrowheaders"
! scope="col" | Co-ordinates
! scope="col" | Country, territory or sea
! scope="col" | Notes
|-
| style="background:#b0e0e6;" | {{Coord|0|N|0|E|type:landmark|name=Prime Meridian}}
! scope="row" style="background:#b0e0e6;" | [[Earth:Atlantic Ocean|Atlantic Ocean]]
| style="background:#b0e0e6;" | Gulf of Guinea, "[[Earth:Null Island|Null Island]]"
|-
| {{Coord|0|0|N|6|31|E|type:country|name=São Tomé and Príncipe}}
! scope="row" | {{STP}}
| Passing through Pestana Equador resort on the Ilhéu das Rolas
|-
| {{Coord|0|0|N|9|21|E|type:country|name=Gabon}}
! scope="row" | {{GAB}}
| Passing {{convert|8.9|km|abbr=on}} south of Ayem, {{convert|10.6|km|abbr=on}} north of Mayene, Booue
|-
| {{Coord|0|0|N|13|56|E|type:country|name=Republic of the Congo}}
! scope="row" | {{COG}}
| Passing through the town of Makoua.
|-
| {{Coord|0|0|N|17|46|E|type:country|name=Democratic Republic of the Congo}}
! scope="row" | {{COD}}
| Passing {{convert|9|km|abbr=on}} south of central Butembo
|-
| {{Coord|0|0|N|29|43|E|type:country|name=Uganda}}
! scope="row" | {{UGA}}
| Passing {{convert|32|km|abbr=on}} south of central [[Place:Kampala|Kampala]]
|-
| style="background:#b0e0e6;" | {{Coord|0|0|N|32|22|E|type:waterbody|name=Lake Victoria}}
! scope="row" style="background:#b0e0e6;" | Lake Victoria
| style="background:#b0e0e6;" | Passing through some islands of {{UGA}} in Mukono District and Namayingo District
|-
| {{Coord|0|0|N|34|0|E|type:country|name=Kenya}}
! scope="row" | {{KEN}}
| Passing {{convert|6|km|abbr=on}} north of central [[Place:Kisumu|Kisumu]]
|-
| {{Coord|0|0|N|41|0|E|type:country|name=Somalia}}
! scope="row" | {{SOM}}
| Passing south of Jamame
|-
| style="background:#b0e0e6;" | {{Coord|0|0|N|42|53|E|type:waterbody|name=Indian Ocean}}
! scope="row" style="background:#b0e0e6;" | [[Earth:Indian Ocean|Indian Ocean]]
| style="background:#b0e0e6;" | Passing between Huvadhu Atoll and Fuvahmulah of the {{MDV}}
|-
| {{Coord|0|0|N|98|12|E|type:country|name=Indonesia}}
! scope="row" | {{IDN}}
| North Sumatra (including the Batu Islands) and Lingga Regency, Riau Islands
|-
| style="background:#b0e0e6;" | {{Coord|0|0|N|104|34|E|type:waterbody|name=Karimata Strait}}
! scope="row" style="background:#b0e0e6;" | Karimata Strait
| style="background:#b0e0e6;" |
|-
| {{Coord|0|0|N|109|9|E|type:country|name=Indonesia}}
! scope="row" | {{IDN}}
| Bornean provinces of West Kalimantan (passing through province capital Pontianak), Central Kalimantan, and East Kalimantan
|-
| style="background:#b0e0e6;" | {{Coord|0|0|N|117|30|E|type:waterbody|name=Makassar Strait}}
! scope="row" style="background:#b0e0e6;" | Makassar Strait
| style="background:#b0e0e6;" | 
|-
| {{Coord|0|0|N|119|40|E|type:country|name=Indonesia}}
! scope="row" | {{IDN}}
| Donggala & Parigi Moutong Regency, Central Sulawesi (Celebes)
|-
| style="background:#b0e0e6;" | {{Coord|0|0|N|120|5|E|type:waterbody|name=Gulf of Tomini}}
! scope="row" style="background:#b0e0e6;" | Gulf of Tomini
| style="background:#b0e0e6;" |
|-
| style="background:#b0e0e6;" | {{Coord|0|0|N|124|0|E|type:waterbody|name=Molucca Sea}}
! scope="row" style="background:#b0e0e6;" | Molucca Sea
| style="background:#b0e0e6;" |
|-
| {{Coord|0|0|N|127|24|E|type:country|name=Indonesia}} 
! scope="row" | {{IDN}}
|Kayoa and Halmahera islands, North Maluku
|-
| style="background:#b0e0e6;" | {{Coord|0|0|N|127|53|E|type:waterbody|name=Halmahera Sea}}
! scope="row" style="background:#b0e0e6;" | Halmahera Sea
| style="background:#b0e0e6;" |
|-
| {{Coord|0|0|N|129|20|E|type:country|name=Indonesia}}
! scope="row" | {{IDN}}
| Gebe and Kawe islands, West Papua
|-
| style="background:#b0e0e6;" | {{Coord|0|0|N|129|21|E|type:waterbody|name=Pacific Ocean}}
! scope="row" style="background:#b0e0e6;" | [[Earth:Pacific Ocean|Pacific Ocean]]
| style="background:#b0e0e6;" | Passing between Aranuka and Nonouti atolls, {{KIR}} (at {{Coord|0|0|N|173|40|E}})
Passing just south of Baker Island, and just north of Jarvis Island, {{UMI}}
|-
| {{Coord|0|0|N|80|6|W|type:country|name=Ecuador}}
! scope="row" | {{ECU}}
| Passing {{convert|24|km|abbr=on}} north of central [[Place:Quito|Quito]], near Mitad del Mundo, and precisely at the location of [[Astronomy:Catequilla|Catequilla]], a [[History:Pre-Columbian era|pre-Columbian]] ruin. Also, Isabela Island in the [[Earth:Galápagos Islands|Galápagos Islands]]
|-
| {{Coord|0|0|N|75|32|W|type:country|name=Colombia}}
! scope="row" | {{COL}}
| Passing {{convert|4.3|km|abbr=on}} north of the border with Peru
|-valign="top"
| {{Coord|0|0|N|70|3|W|type:country|name=Brazil}}
! scope="row" | {{BRA}}
| Amazonas, Roraima, Pará, Amapá (passing slightly south of the city center of the state capital Macapá, and precisely at the Marco Zero monument and the Avenue Equatorial)
|-
| style="background:#b0e0e6;" | {{Coord|0|0|N|49|21|W|type:waterbody|name=Atlantic Ocean}}
! scope="row" style="background:#b0e0e6;" | [[Earth:Atlantic Ocean|Atlantic Ocean]]
| style="background:#b0e0e6;" | At the Perigoso Canal (''<small>sv</small>'') on the mouth of the Amazon River
|-
|}

Despite its name, no part of Equatorial Guinea lies on the equator. However, its island of Annobón is {{convert|155|km|abbr=on}} south of the equator, and the rest of the country lies to the north.

==Equatorial seasons and climate==
[[File:seasons.svg|frame|right|<br/>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 will be dark, and the South Pole will be illuminated; see also arctic winter. In addition to the density of incident light, the [[Dissipation|dissipation]] of light in the atmosphere is greater when it falls at a shallow angle.]]

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 [[Astronomy:Solstice|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.

Near the equator, this means the variation in the strength of solar radiation is different relative to the time of year than it is at higher latitudes: Maximum solar radiation is received during the equinoxes, when a place at the equator is under the [[Astronomy:Subsolar point|subsolar point]] at high noon, and the intermediate seasons of spring and autumn occur at higher latitudes, and the minimum occurs during ''both'' solstices, when either pole is tilted towards or away from the sun, resulting in either summer or winter in both hemispheres. This also results in a corresponding movement of the equator away from the subsolar point, which is then situated over or near the relevant tropic circle. Nevertheless, temperatures are high year round due to the earth's [[Astronomy:Axial tilt|axial tilt]] of 23.5° not being enough to create a low minimum midday [[Astronomy:Position of the Sun|declination]] to sufficiently weaken the sun's rays even during the solstices.

Near the 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 generally have a [[Earth:Tropical rainforest climate|tropical rainforest climate]], also known as an equatorial climate, though cold ocean currents cause some regions to have [[Earth:Tropical monsoon climate|tropical monsoon climate]]s with a [[Earth:Dry season|dry season]] in the middle of the year, and the [[Earth:Somali Current|Somali Current]] generated by [[Earth:Monsoon of South Asia|the Asian monsoon]] due to continental heating via the high [[Place:Tibetan Plateau|Tibetan Plateau]] causes [[Place:Greater Somalia|Greater Somalia]] to have an arid climate despite its equatorial location.

Average annual temperatures in equatorial lowlands are around {{convert|31|°C|°F|abbr=on}} during the afternoon and {{convert|23|°C|°F|abbr=on}} around sunrise. Rainfall is very high away from cold ocean current upwelling zones, from {{convert|2500|to|3500|mm|abbr=on|round=5}} 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 [[Place:Andes|Andes]] and [[Earth:Mount Kilimanjaro|Mount Kilimanjaro]] have glaciers. The highest point on the equator is at the elevation of {{convert|4690|m|0}}, at {{coord|0|0|0|N|77|59|31|W|type:landmark_region:EC|name=highest point on the equator}}, found on the southern slopes of Volcán Cayambe [summit {{convert|5790|m|0}}] in Ecuador. This is slightly above the [[Earth:Snow line|snow line]] and is the only place on the equator where snow lies on the ground. At the equator, the snow line is around {{convert|1000|m|ft}} ''lower'' than on [[Earth:Mount Everest|Mount Everest]] and as much as {{convert|2000|m|ft}} lower than the highest snow line in the world, near the Tropic of Capricorn on [[Earth:Llullaillaco|Llullaillaco]].
<div style="width:85%;">
{{Weather box|location = Macapá, {{wipe|Brazil}} in South America
|metric first = yes
|single line = yes
|Jan high C = 29.7
|Feb high C = 29.2
|Mar high C = 29.3
|Apr high C = 29.5
|May high C = 30.0
|Jun high C = 30.3
|Jul high C = 30.6
|Aug high C = 31.5
|Sep high C = 32.1
|Oct high C = 32.6
|Nov high C = 32.3
|Dec high C = 31.4
|year high C = 30.71
|Jan mean C = 26.5
|Feb mean C = 26.2
|Mar mean C = 26.3
|Apr mean C = 26.4
|May mean C = 26.8
|Jun mean C = 26.8
|Jul mean C = 26.8
|Aug mean C = 27.4
|Sep mean C = 27.8
|Oct mean C = 28.1
|Nov mean C = 27.9
|Dec mean C = 27.4
|year mean C = 27.03
|Jan low C = 23.0
|Feb low C = 23.1
|Mar low C = 23.2
|Apr low C = 23.5
|May low C = 23.5
|Jun low C = 23.2
|Jul low C = 22.9
|Aug low C = 23.3
|Sep low C = 23.4
|Oct low C = 23.5
|Nov low C = 23.5
|Dec low C = 23.4
|year low C = 23.29
|rain colour=green
|Jan rain mm = 299.6
|Feb rain mm = 347.0
|Mar rain mm = 407.2
|Apr rain mm = 384.3
|May rain mm = 351.5
|Jun rain mm = 220.1
|Jul rain mm = 184.8
|Aug rain mm = 98.0
|Sep rain mm = 42.6
|Oct rain mm = 35.5
|Nov rain mm = 58.4
|Dec rain mm = 142.5
|Jan rain days = 23
|Feb rain days = 22
|Mar rain days = 24
|Apr rain days = 24
|May rain days = 25
|Jun rain days = 22
|Jul rain days = 19
|Aug rain days = 13
|Sep rain days = 6
|Oct rain days = 5
|Nov rain days = 6
|Dec rain days = 14
|unit rain days = 0.1&nbsp;mm
|Jan sun = 148.8
|Feb sun = 113.1
|Mar sun = 108.5
|Apr sun = 114.0
|May sun = 151.9
|Jun sun = 189.0
|Jul sun = 226.3
|Aug sun = 272.8
|Sep sun = 273.0
|Oct sun = 282.1
|Nov sun = 252.0
|Dec sun = 204.6
|year sun = 2336.1
|source 1 = [[Organization:World Meteorological Organization|World Meteorological Organization]] ({{wipe|United Nations}}),<ref>{{cite web
 |url=http://www.worldweather.org/136/c01071.htm
 |title=Weather Information for Macapa
 |website = World Weather Information Service 
 |publisher = World Meteorological Organization}}</ref> [[Organization:Hong Kong Observatory|Hong Kong Observatory]]<ref>{{cite web|url = http://www.weather.gov.hk/wxinfo/climat/world/eng/s_america/brazil/macapa_e.htm |title = Climatological Normals of Macapa|website =Hong Kong Observatory |archive-url =https://web.archive.org/web/20191026000816/http://www.weather.gov.hk/wxinfo/climat/world/eng/s_america/brazil/macapa_e.htm |archive-date = 26 October 2019}}</ref>
|date=March 2011}}

{{Weather box|location = Pontianak, Indonesia in Asia
|metric first = yes
|single line = yes
|Jan high C = 32.4
|Feb high C = 32.7
|Mar high C = 32.9
|Apr high C = 33.2
|May high C = 33.0
|Jun high C = 33.2
|Jul high C = 32.9
|Aug high C = 33.4
|Sep high C = 32.6
|Oct high C = 32.6
|Nov high C = 32.2
|Dec high C = 32.0
|year high C = 32.7
|Jan mean C = 27.6
|Feb mean C = 27.7
|Mar mean C = 28.0
|Apr mean C = 28.2
|May mean C = 28.2
|Jun mean C = 28.2
|Jul mean C = 27.7
|Aug mean C = 27.9
|Sep mean C = 27.6
|Oct mean C = 27.7
|Nov mean C = 27.4
|Dec mean C = 27.2
|year mean C = 27.7
|Jan low C = 22.7
|Feb low C = 22.6
|Mar low C = 23.0
|Apr low C = 23.2
|May low C = 23.4
|Jun low C = 23.1
|Jul low C = 22.5
|Aug low C = 22.3
|Sep low C = 22.6
|Oct low C = 22.8
|Nov low C = 22.6
|Dec low C = 22.4
|year low C = 22.7
|rain colour=green
|Jan rain mm = 260
|Feb rain mm = 215
|Mar rain mm = 254
|Apr rain mm = 292
|May rain mm = 256
|Jun rain mm = 212
|Jul rain mm = 201
|Aug rain mm = 180
|Sep rain mm = 295
|Oct rain mm = 329
|Nov rain mm = 400
|Dec rain mm = 302
|Jan rain days = 15
|Feb rain days = 13
|Mar rain days = 21
|Apr rain days = 22
|May rain days = 20
|Jun rain days = 18
|Jul rain days = 16
|Aug rain days = 25
|Sep rain days = 14
|Oct rain days = 27
|Nov rain days = 25
|Dec rain days = 22
|unit rain days = 0.1&nbsp;mm
|source 1 = [[Organization:World Meteorological Organization|World Meteorological Organization]] ({{wipe|United Nations}})<ref>{{cite web
 |url=http://www.worldweather.org/043/c00653.htm
 |title=Weather Information for Pontianak
 |website = World Weather Information Service
 |publisher = World Meteorological Organization}}</ref>
|date=March 2011}}

{{Weather box|location = [[Place:Libreville|Libreville]], Gabon in Africa
|metric first = yes
|single line = yes
|Jan high C = 29.5
|Feb high C = 30.0
|Mar high C = 30.2
|Apr high C = 30.1
|May high C = 29.4
|Jun high C = 27.6
|Jul high C = 26.4
|Aug high C = 26.8
|Sep high C = 27.5
|Oct high C = 28.0
|Nov high C = 28.4
|Dec high C = 29.0
|year high C = 28.58
|Jan mean C = 26.8
|Feb mean C = 27.0
|Mar mean C = 27.1
|Apr mean C = 26.6
|May mean C = 26.7
|Jun mean C = 25.4
|Jul mean C = 24.3
|Aug mean C = 24.3
|Sep mean C = 25.4
|Oct mean C = 25.7
|Nov mean C = 25.9
|Dec mean C = 26.2
|year mean C = 25.95
|Jan low C = 24.1
|Feb low C = 24.0
|Mar low C = 23.9
|Apr low C = 23.1
|May low C = 24.0
|Jun low C = 23.2
|Jul low C = 22.1
|Aug low C = 21.8
|Sep low C = 23.2
|Oct low C = 23.4
|Nov low C = 23.4
|Dec low C = 23.4
|year low C = 23.30
|rain colour=green
|Jan rain mm = 250.3
|Feb rain mm = 243.1
|Mar rain mm = 363.2
|Apr rain mm = 339.0
|May rain mm = 247.3 
|Jun rain mm = 54.1
|Jul rain mm = 6.6
|Aug rain mm = 13.7
|Sep rain mm = 104.0
|Oct rain mm = 427.2
|Nov rain mm = 490.0
|Dec rain mm = 303.2
|Jan rain days = 17.9
|Feb rain days = 14.8
|Mar rain days = 19.5
|Apr rain days = 19.2
|May rain days = 16.0
|Jun rain days = 3.70
|Jul rain days = 1.70
|Aug rain days = 4.90
|Sep rain days = 14.5
|Oct rain days = 25.0
|Nov rain days = 22.6
|Dec rain days = 17.6
|unit rain days = 0.1&nbsp;mm
|Jan sun = 176.7
|Feb sun = 182.7
|Mar sun = 176.7
|Apr sun = 177.0
|May sun = 158.1
|Jun sun = 132.0
|Jul sun = 117.8
|Aug sun = 89.90
|Sep sun = 96.00
|Oct sun = 111.6
|Nov sun = 135.0
|Dec sun = 167.4
|year sun = 1720.9
|source 1 = [[Organization:World Meteorological Organization|World Meteorological Organization]] ({{wipe|United Nations}}),<ref>{{cite web
 |url=http://www.worldweather.org/128/c00255.htm
 |title=Weather Information for Libreville
 |website = World Weather Information Service
 |publisher = World Meteorological Organization}}</ref> [[Organization:Hong Kong Observatory|Hong Kong Observatory]]<ref>{{cite web|url = http://www.weather.gov.hk/wxinfo/climat/world/eng/africa/nig_cam/libreville_e.htm |title = Climatological Normals of Libreville|website = Hong Kong Observatory |archive-url =https://web.archive.org/web/20191026001210/http://www.weather.gov.hk/wxinfo/climat/world/eng/africa/nig_cam/libreville_e.htm|archive-date = 26 October 2019}}</ref>
|date=March 2011}}
</div>

==Line crossing ceremonies==
There is a widespread maritime tradition of holding ceremonies to mark a sailor's first crossing of the equator. In the past, these ceremonies have been notorious for their brutality, especially in naval practice. {{citation needed|date=April 2017}} Milder line-crossing ceremonies, typically featuring King Neptune, are also held for passengers' entertainment on some civilian ocean liners and cruise ships.{{citation needed|date=January 2015}}

==See also==
{{div col}}
* 1st parallel north
* 1st parallel south
* Coriolis effect
* [[Earth:Intertropical Convergence Zone|Intertropical Convergence Zone]]
* Prime meridian
* [[Earth:Thermal equator|Thermal equator]]
* Bogota Declaration
* Planetary equator
{{div col end}}

==References==
{{reflist}}

==Sources==
{{refbegin}}
* {{cite journal |title=Geodetic Reference System 1980 |journal=Bulletin Géodésique |publisher=[[Physics:Springer-Verlag|Springer-Verlag]] |location=[[Place:Berlin|Berlin]] |first=H |last=Moritz |pages=395–405 |volume=54 |issue=3 |date=September 1980 |doi=10.1007/BF02521480|bibcode = 1980BGeod..54..395M |s2cid=198209711 }} (IUGG/WGS-84 data)
* {{cite book |title=Computational Spherical Astronomy |publisher=Wiley |location={{wipe|New York City}} |first=Laurence G |last=Taff |year=1981 |isbn=0-471-06257-X |oclc=6532537}} (IAU data)
{{refend}}

[[Category:Celestial coordinate system]]
[[Category:Geodesy]]

{{Sourceattribution|Equator|1}}