What is Meridian (geography)?

Information about Meridian (geography)

This article is about the geographical concept. For other uses of the word, see Meridian.
Enlarge picture
The prime meridian at Greenwich, England
A meridian (or line of longitude) is an imaginary arc on the Earth's surface from the North Pole to the South Pole that connects all locations with a given longitude. The position of a point on the meridan is given by the latitude. Each meridian is perpendicular to all circles of latitude at the intersection points. Each is also the same size, being half of a great circle on the Earth's surface and therefore measuring 20,003.93 km.

Since the meridian that passes through Greenwich, England, establishes the meaning of zero degrees of longitude, or the Prime Meridian, any other meridian is identified by the angle, referenced to the center of the earth as vertex, between where it and the prime meridian cross the equator. As there are 360 degrees in a circle, the meridian on the opposite side of the earth from Greenwich (which forms the other half of a circle with the one through Greenwich) is 180° longitude, and the others lie between 0° and 180° of West longitude in the Western Hemisphere (west of Greenwich) and between 0° and 180° of East longitude in the Eastern Hemisphere (east of Greenwich). You can see the lines of longitude on most maps.

The term "meridian" comes from the Latin meridies, meaning "midday"; the sun crosses a given meridian midway between the times of sunrise and sunset on that meridian. The same Latin stem gives rise to the terms A.M. and P.M. used to disambiguate hours of the day when using the 12-hour clock.

See also

For meridians used as references in surveying:
This article originates from Jason Harris' Astroinfo which comes along with KStars, a Desktop Planetarium for Linux/KDE. See [1]
Meridian may refer to:

Earth science

  • Meridian (astronomy), imaginary circle perpendicular to the celestial equator and horizon
  • Meridian (geography), imaginary line on the Earth's surface from the North Pole to the South Pole

..... Read more.
North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets the Earth's surface.
..... Read more.
South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is the southernmost point on the surface of the Earth. It lies on the continent of Antarctica, on the opposite side of the Earth from the North Pole.
..... Read more.
equator divides the planet into a Northern Hemisphere and a Southern Hemisphere, and has a latitude of 0. Longitude is the east-west geographic coordinate measurement most commonly utilized in cartography and global navigation.
..... Read more.
equator divides the planet into a Northern Hemisphere and a Southern Hemisphere, and has a latitude of 0. Latitude, usually denoted symbolically by the Greek letter phi, , gives the location of a place on Earth north or south of the equator.
..... Read more.
equator divides the planet into a Northern Hemisphere and a Southern Hemisphere, and has a latitude of 0. On the Earth, a circle of latitude is an imaginary east-west circle connecting all locations that have a given latitude.
..... Read more.
  • Great circle is a circle on the surface of a sphere.
  • Great Circle is also a fictional organization from Andromeda Nebula, a novel by Ivan Yefremov
A great circle
..... Read more.
Royal Observatory, Greenwich (formerly the Royal Greenwich Observatory or RGO) was commissioned in 1675 by King Charles II, with the foundation stone being laid on 10 August.
..... Read more.
Prime Meridian, also known as the International Meridian or Greenwich Meridian, is the meridian (line of longitude) passing through the Royal Greenwich Observatory in London — it is the meridian at which longitude is defined to be 0 degrees.
..... Read more.
Western Hemisphere, also Western hemisphere[1] or western hemisphere,[2] is a geographical term for the half of the Earth that lies west of the Prime Meridian (which crosses Greenwich in London, England, United Kingdom), the other half being the
..... Read more.
Eastern Hemisphere, also Eastern hemisphere[1] or eastern hemisphere,[2] is a geographical term for the half of the Earth that is east of the Prime Meridian (which crosses Greenwich, England, United Kingdom) and west of the International Date
..... Read more.
The 12-hour clock is a timekeeping convention in which the 24 hours of the day are divided into two periods called ante meridiem (a.m., from Latin, meaning "before mid day", or "before the middle of the day") and post meridiem (
..... Read more.
The 12-hour clock is a timekeeping convention in which the 24 hours of the day are divided into two periods called ante meridiem (a.m., from Latin, meaning "before mid day", or "before the middle of the day") and post meridiem (
..... Read more.
Prime Meridian, also known as the International Meridian or Greenwich Meridian, is the meridian (line of longitude) passing through the Royal Greenwich Observatory in London — it is the meridian at which longitude is defined to be 0 degrees.
..... Read more.
The Public Land Survey System (PLSS) is a method used in the United States to survey and identify land parcels, particularly for titles and deeds of rural, wild or undeveloped land. Its basic units of area are the township and section.
..... Read more.
The Dominion Land Survey is the method used to divide most of Western Canada into one-square-mile sections for agricultural and other purposes. It is based on the layout of the Public Land Survey System used in the United States, but has several differences.
..... Read more.
KStars is a planetarium program for the KDE desktop for Unix-like computer operating systems. It provides an accurate graphical representation of the night sky, from any location on Earth, at any date and time.
..... Read more.
Linux (pronunciation: IPA: /ˈlɪnʊks/, lin-uks) is a Unix-like computer operating system. Linux is one of the most prominent examples of free software and open source development; its underlying source code can be
..... Read more.
Maintainer: The KDE Team

OS: Cross-platform
Available language(s): Multilingual (80 different languages.)
Use: Desktop environment
License: GNU General Public License and others
Website: [1] KDE (
..... Read more.