There is no unequivocal answer to the question of what a meridian is. Therefore, let's start in order and see in which sciences and in which areas this concept is applied.

The word "meridian" comes from the Latin word which means "noon".

1. Astronomical meridian, or as it is also called, the true meridian. In astronomy, a meridian is a line that passes through both poles of the world, as well as the zenith (the point of the celestial sphere that is directly above the observer's head) and nadir (the point that is opposite the zenith, that is, is directly under the feet of the observer). We have all seen this meridian in astronomy and geography textbooks. All points of this invisible line have the same astronomical longitude.

2. The celestial meridian almost always coincides with the astronomical meridian, that is, the line that also passes through the poles of the world and the zenith above the observer's head.

3. The Greenwich Meridian is, perhaps, the meridian that is known to everyone all over the world. The Royal Greenwich Observatory is the most important and basic astronomical organization in England. It was founded in 1675 and since then it has functioned like clockwork. However, today this observatory is a museum, which is the most visited museum in England. It is through this observatory that the prime meridian passes, which is the origin of longitude on the globe. This event took place in 1851. For a very long time after that, the prime meridian itself was marked with a special brass ribbon that ran right through the courtyard of the observatory. Over time, this tape was replaced by another - made of stainless steel, and today the prime meridian is marked with a green laser beam, which is directed to the north.

4. The meridian is geodetic. This meridian is a conditional line that runs along the surface of the earth and all points that are located on it have the same geodetic longitude.

5. The cartographic meridian passes through the axis of rotation of the Earth and is most often drawn on a paper image of the globe.

However, there are many more meridians. This is the name of cities and rivers, nightclubs and music groups, spacecraft and travel companies, newspapers and magazines ... Many things in our world are called the word "meridian". This fashion has not spared our city either. We have a small shop under the proud name "Meridian". When I asked a saleswoman I knew why it was called that, she looked at me with incredible surprise, but decided to ask the director.

The next day I received an answer. It turns out, according to the director, the meridian is the place where the rays of light converge. And so the buyers are these same rays, and the store is the place of their gathering. I was a little shocked by this answer, and then asked how old this director was. It turned out that he was 41 years old ...

Here is one more explanation for what "Meridian" is, although it does not fit the celestial or astronomical meridian at all, but, apparently, it fits very precisely to this shop ...

The coordinates and location of any object on the globe can be determined by knowing the latitude and longitude of the point. Let's find out what are the subtleties of the meaning of each of them.

How to determine coordinates

Any modern geographic map makes it possible to find the coordinates of any city, mountain or lake. You need to know the indicators of latitude and longitude.

With the first, everything is clear: it is determined relative to the equator - an imaginary line that runs at the place where the plane perpendicular to the axis of the Earth intersects the center of our planet. It is the start of the countdown, a kind of "zero" for finding the value of latitude, the location of the parallels. The Equator passes through several countries - Congo, Kenya, Uganda, Somalia in Africa, Indonesia located on the Sunda Islands, Ecuador, Brazil, Colombia in the Equator gives a clear idea of ​​latitude.

Longitude is another matter. For a long time there was no consensus on what to take as the basis for this coordinate. Longitude is the determination of the position of a point on the surface of the Earth relative to the zero point of reference from which the meridians depart. These are also imaginary lines that make it easier to work with maps. The angle between each of them and the origin is longitude. The zero meridian is the base of this coordinate.

Longitude problem

If everything is clear with the equator, then what the "prime meridian" is was not immediately clear. For many years in different countries they used their "zero". Of course, this created confusion.

Every country respecting science in the 19th century has already acquired an observatory for observing celestial bodies. She was the reference point for longitude. Russia, the USA, Great Britain and France had their own initial positions of the meridians.

Longitude is very important in maritime navigation. And long before the formation of clear scientific reference systems, there were other methods that made it possible not to get lost at sea. The first option was proposed by Johann Werner. The bottom line is observing the moon. Another method belongs to the genius Galileo Galilei. Using a telescope, he observed the position. The disadvantage of this method is the need for complex instruments.

A simpler method - determination using the difference between local and exact time at a reference point - belongs to the authorship of Frisius Gemme. But not everyone had such an accurate watch either.

Meridian zero has become a kind of Grail - for the accurate determination of longitude in Britain they even offered a huge premium. Then the problem was in the invention of precise clocks. What is the prime meridian, then they did not know exactly.

The clock was invented after all. John Harrison received the prize for them. But in navigation they continued to use the old methods. The turning point was the moment of the invention of radio. Modern sailors use satellite data to determine longitude.

Reference points

As already mentioned, every country that had an observatory made it the reference point for longitude. The meridian of the same name passes through the Paris Observatory. It was popular in the 19th century.

In Russia, the zero meridian was named Pulkovsky. It got its name from an observatory located near St. Petersburg. Used primarily in Russia. This "zero" meridian passes through Mogilev, Kiev region, Lake Tanganyika in Africa, the pyramids of Egypt. Not used at the present stage.

The Ferro meridian passing through the Canary island of the same name was popular. First used by Ptolemy.

Since the 19th century, the Greenwich meridian has been used in England. He was fixed as a "zero" for longitude in the modern world.

The Greenwich Prime Meridian is an imaginary line running through London. With Pulkovsky, he has a difference of 30 degrees, with the Parisian - 2.

Meridian conference

In 1884, eminent geographers and politicians gathered in Washington to settle the coordinate reference system. The International Meridian Conference brought together representatives from Russia, Austria-Hungary, Germany, Great Britain, France, Denmark, Chile, Venezuela, Japan, Switzerland, the Ottoman Empire and many other countries. A total of 41 representatives attended.

In addition to determining the longitude, the participants were interested in the development of a time reckoning system. What is the problem? And the fact is that up to the 19th century, a single unified time did not exist. All used local units. This caused confusion. The lack of standards hindered trade between countries with different levels of development of science and culture. There were also problems with transport.

Where should the longitude start

Of all the existing starting points, one had to choose one. The decision was taken by an open vote, in which all the delegates present participated.

At the conference they decided which object should become the reference point for longitude. Meridian zero, according to the delegates' proposals, could pass through Paris, the Azores or the Canary Islands, the Bering Strait, Greenwich. The islands immediately lost in votes - there was no proper level of scientific support. Paris, too, did not receive votes. Ferro, while popular, was also rejected. London's prime meridian was victorious, only France objected.

A little about time

The first to talk about the need to unify the standards of the times was Mr. Sandford Fleming, a simple Canadian engineer. One day, due to time confusion, he missed a train and missed an important meeting. Thus, from 1876, Fleming pushed for reform.

The issue was resolved at the aforementioned conference in Washington. A system of time zones was formed, which is still used today. Not everyone accepted the innovations. For example, Russia joined the standard only in 1919. Germany, France and Austria-Hungary also joined later.

The reference point is the prime meridian. This imaginary line runs over oceans, seas, land. The borders of 24 belts are meridians. However, until now, not everyone follows this division. The reasons for this are the size of the countries. are also in Greenwich. By the way, the GPS system shows the origin of longitude not at the observatory, but 100 meters away from it.

Greenwich observatory

The Center for Astronomical Research in Great Britain and the origin of longitude is the Observatory in Greenwich. This place has a rich history. It was founded in the 17th century by the efforts of King Charles II. During its existence, the observatory changed its location. The very idea of ​​creating such an institution did not belong to the king, but to statesman Jonas Moore. He convinced the king of the importance of the observatory, and proposed to make John Flamsteed the chief astronomer. The building was soon designed and built, with the lion's share of the funding on Moore's shoulders.

The exact clock and time standard were set here. As you know, the longitude reference passes through the observatory. At the local level, the Greenwich meridian began to be used as early as 1851, and was approved at the famous conference in 1884.

They tried to blow up the observatory once! At the time of 1894, this was a unique, first case in British history.

At the present stage, the observatory continues to function. Various instruments for research in the field of astronomy are located here. In fact, this is a museum, which houses many of the most valuable exhibits. They reflect the history of science and technology, especially in the field of time measurements. Recently, reconstruction was carried out, a planetarium and galleries were created.

Conclusion

Zero meridian is a reference point for longitude and time. But this term can be used in other areas as well. So, in 2006, the Zero Meridian collective became popular in Russia. "Not My Words" is the most famous song of this group.

Longitude has been counted from Greenwich for many years. Lines depart from the prime meridian, along which coordinates are determined in all parts of the world. It splits into the east and passes the prime meridian through Algeria, Ghana, Mali, Spain, Great Britain, France. Thus, these countries are located in both hemispheres at the same time.

If our planet is "cut" through the axis of rotation and perpendicular to it with many planes, then vertical and horizontal circles - meridians and parallels - will appear on the surface.


The meridians will converge at two points - at the North and South Poles. Parallels, as the name suggests, are parallel to each other. Meridians are used to measure longitude, parallels - latitude.

Such a simple at a superficial glance, the action - "ruling" the Earth - has become the greatest discovery in the study of the planet. It allowed us to use coordinates and accurately describe the location of any object. Without parallels and meridians, it is impossible to imagine a single map, not a single globe. And invented them ... in the III century BC, the Alexandrian scientist Eratosthenes.

Reference. Eratosthenes possessed knowledge encyclopedic for those times in all areas. He was in charge of the legendary Library of Alexandria, wrote the work "Geography" and became the founder of geography as a science, made the first map of the world and covered it with a degree grid of vertical and horizontal lines - invented a coordinate system. He also introduced the names for the lines - parallel and meridian.

Meridian

The meridian in geography is called half of the section line of the earth's surface, drawn through any point on the surface. All imaginary meridians, of which there can be an infinite number, are connected at the poles - North and South. The length of each of them is 20,004,276 meters.

Although you can mentally draw as many meridians as you like, for the convenience of movement, drawing up maps, their number and location have been streamlined by international treaties. In 1884, at the International Meridian Conference in Washington, it was decided that the initial meridian (zero) would be the one that passes through Greenwich, a district in southeast London.

However, not everyone immediately agreed with this decision. For example, in Russia, even after 1884, until the beginning of the twentieth century, Pulkovsky was considered the zero meridian: it “passes” through the Round Hall of the Pulkovo Observatory.

Prime Meridian

The zero meridian is the reference point of geographical longitude. He himself, accordingly, has a zero longitude. This was the case before the creation of the world's first satellite navigation system, Transit.


With its appearance, the prime meridian had to be slightly shifted - at 5.3 ″ relative to Greenwich Mean Time. This is how the International Reference Meridian appeared, which is used as a reference point for longitude by the International Earth Rotation Service.

Parallel

Parallels in geography are called lines of an imaginary section of the planet's surface by planes that are parallel. The parallels shown on the globe are circles parallel to the equator. Geographic latitude is measured with their help.

By analogy with the Greenwich prime meridian, there is also a zero parallel - this is the equator, one of the 5 main parallels that divides the Earth into hemispheres - southern and northern. Other main parallels are the North and South tropics, and the North and South polar circles.

Equator

The longest parallel is the equator - 40,075,696 m. The rotation speed of our planet at the equator is 465 m / s - much more than the speed of sound propagation in air - 331 m / s.

Southern and Northern tropics

The Southern Tropic, also called the Tropic of Capricorn, lies south of the equator and represents the latitude above which the noon is at its zenith on the winter solstice.

The Northern Tropic, also known as the Tropic of Cancer, is located north of the equator and, like the southern tropic, represents the latitude above which the midday sun stands at its zenith on the summer solstice.

Arctic Circle and Antarctic Circle

The Arctic Circle is the border of the polar day area. To the north of it, anywhere at least once a year, the sun is visible above the horizon 24 hours a day, or the same amount is not visible.

The Antarctic Circle is similar in every way to the North, only it is located in the southern hemisphere.

Degree grid

The intersections of meridians and parallels form a degree grid. Meridians and parallels are located at intervals of 10 ° - 20 °, smaller divisions, as in the corners, are called minutes and seconds.


With the help of a degree grid, we determine the exact location of geographic objects - their geographic coordinates, calculating longitude by meridians, and latitude by parallels.

All dictionaries Ushakov's dictionary Naval Dictionary Explanatory dictionary of the Russian language (Alabugin) Brief dictionary of operational-tactical and general military terms Encyclopedic dictionary Ozhegov's dictionary Efremova's dictionary Explanatory dictionary of the living Great Russian language, Dal Vladimir

Ushakov's Dictionary

meridian

meridia n, meridian, husband. (lat. meridianus, letters. midday). In geography: an imaginary circular line passing through the poles of the globe and crossing the equator at right angles. Earth meridian. The first meridian divides the earth into east and app. hemisphere.

| In astronomy: an imaginary circle passing through the poles of the world.

Naval Dictionary

meridian

1) geographical - the line of intersection of the surface of the earth's ellipsoid with a plane passing through the North and South geographic poles. Each meridian has the same longitude. The geographic meridian passing through the observation point is called the observer's meridian.

2) The celestial meridian is a large circle of the celestial sphere passing through the poles of the world.

Explanatory dictionary of the Russian language (Alabugin)

meridian

A, m.

An imaginary circular line running through the poles of the globe and crossing the equator at right angles.

* Prime Meridian. *

|| adj. meridian, th, th and meridional, th, th.

* Meridian circle. Meridional direction. *

A short dictionary of operational-tactical and general military terms

meridian

the line of intersection of the earth's surface with a vertical plane passing through a given point and the earth's axis. M. in combination with parallels (lines of intersection of the earth's surface by planes parallel to the section along the equator) form a degree network of the globe, the main lines of which are the Greenwich (initial) M. and the equator.

encyclopedic Dictionary

meridian

(from Lat. meridianus - noon) geographical, a line of section of the surface of the globe by a plane drawn through any point on the earth's surface and the axis of rotation of the Earth. Initial meridian - the meridian from which the geographic longitude is calculated; in international practice, Greenwich is adopted as the initial meridian.

Ozhegov Dictionary

meridian

MERIDI A H, a, m. An imaginary line passing through the poles of the globe and crossing the equator. Geographic m. Initial m. (the meridian of the Greenwich Observatory in Great Britain, from which the geographic longitude is conventionally calculated).

Heavenly meridian(special) a large circle of the celestial sphere passing through the zenith and the poles of the world.

| adj. meridian, oh, oh and meridional, oh, oh. Meridian circle (astronomical instrument). Meridional time.

Efremova's Dictionary

meridian

m.
An imaginary closed curved line passing through the poles of the globe and below
crossing the equator at right angles (in geography).

Explanatory Dictionary of the Living Great Russian Language, Dal Vladimir

meridian

m. a midday, an imaginary large circle in the sky (that is, the plane of which passes through the center of the earth) through the poles, perpendicular to the equinox, and a circle corresponding to it on the earth's surface.

Usually, they mean only the floor or even a quarter of a circle of this, namely the part passing through the crown (zenith) of the observer or terrain. The sun rolls across the midday, and coming to it, gives each place consecutive noon. The first meridian, from which the longitude of the place is considered, is taken at will: Fero, Grinich, Paris, etc. Meridian, midday, related to the meridian. -th height of the sun, noon, highest. - a new line, a line drawn on a board set on a level, in the direction of a midday, for example, for a sundial, for checking compasses; this line points to north and south. circle, an astronomical projectile set in the direction of the meridian.