Have you ever wondered how it's possible to locate an exact point on our planet? The secret lies in a system of imaginary lines that cross the Earth: meridians and parallels. These lines form the basis of modern cartography and navigation, and although you can't see them, their importance is incalculable. They allow us to orient ourselves, understand time zones, plan trips and even predict the weather., being the backbone on which all geographical knowledge is based.
In this article, we'll take a deep dive into what meridians and parallels are, how they came to be, what they're used for, and why they remain so relevant in today's world. You'll discover its main characteristics, how they relate to latitude and longitude, its practical applications from ancient times to modern GPS systems, and some interesting facts that will surprise even the most clueless. Prepare to see the Earth through new eyes and understand its geographic distribution like never before.
What are meridians and parallels?
Meridians and parallels are the fundamental imaginary lines that divide and segment the globe to facilitate the location of any place on the Earth's surface. Although they cannot be seen with the naked eye, their function has been crucial since early cartographers sought to capture the world in understandable and useful maps.
The meridians They are imaginary lines that run from one pole to the other, forming vertical semicircles on our planet. These lines allow us to measure longitude, that is, the east-west position of any point relative to a reference meridian: the famous Greenwich Meridian.
The parallels, on the other hand, are concentric, horizontal circles that surround the Earth from the equator to the poles. They are used to measure latitude, the north-south distance from the equator, which is the longest parallel and divides the planet into two hemispheres: northern and southern.
The combination of both systems results in a perfect grid on the planet's surface., known as the "geographic network", which allows the position of any point to be indicated by two values: latitude (north or south) and longitude (east or west).
Main characteristics of meridians and parallels
Each type of line has its own characteristics and performs different functions in geography and navigation. We explain it to you clearly and simply so that you never confuse them again:
- The meridians They are always semicircles of the same size that converge at the poles, stretching from north to south. The most important is the Greenwich Mean Time, from which longitude is measured (from 0° to 180° east or west).
- The parallels They are complete circles, parallel to each other and to the equator. The equator is the 0° parallel and the largest of all; the closer to the poles, the smaller the parallels.
- Both systems together establish a geographic coordinate system which, with just two values, allows you to say exactly where anything on the planet is.
- They are also used to define time zones, climatic zones, borders and even astronomical phenomena such as solstices and equinoxes.
What are meridians and parallels really for?
Beyond theory, meridians and parallels have practical applications that we all use without realizing it.One of its main functions is to facilitate orientation and location on Earth:
- They allow to determine exact geographic coordinates (latitude and longitude) to locate countries, cities, mountains, oceans or any desired point.
- They are essential in maritime and air navigation, where safety and precision depend on an exact position.
- They define time zones and time zones at a global level, determining the time differences between different regions.
- They are used in meteorology and climate studies., helping to identify climatic zones and atmospheric phenomena characteristic of each area.
Origin and history of the system of meridians and parallels
Where did this idea of drawing invisible lines on a spherical planet come from? The concept of dividing the Earth by meridians and parallels dates back to ancient times. As early as classical Greece, figures such as Eratosthenes and Hipparchus devised the first coordinate systems for locating places and calculating distances.
With the advent of great voyages and the development of cartography in the Middle Ages and the Modern Age, the current system we use today was perfectedThe reference meridian, known as the Greenwich Meridian, was universally accepted in 1884 during the International Meridian Conference in Washington, due to the maritime and scientific importance of the United Kingdom.
El Ecuador and other main parallels were established as a reference for their astronomical relevance, dividing the Earth into different climatic zones and hemispheres.
Navigation, exploration and, in modern times, telecommunications They have consolidated and sophisticated this system, allowing positions to be calculated even with atomic clocks and satellites.
The most important parallels and their geographical function
Among the hundreds of parallels that could be drawn, five stand out for their geographical, climatic, and astronomical significance. They are much more than simple lines on maps: they correspond to boundaries and areas where unique phenomena occur.
- Ecuador (0°): The most important one divides the Earth into the northern and southern hemispheres and marks the point of maximum solar radiation.
- Tropic of Cancer (23,5° north): It marks the northern limit where the sun can be at its zenith.
- Tropic of Capricorn (23,5° south): Southern limit of the previous phenomenon.
- Arctic Circle (66,5° north): Area where the midnight sun phenomenon or polar night can occur.
- Antarctic Circle (66,5° south): Equivalent to the previous one in the southern hemisphere.
These parallels segment the Earth into bands that determine the main climates of the planet.: equatorial, tropical, temperate and polar zones.
The most important meridians: Greenwich and the antimeridian
As for the meridians, the two best known are the Greenwich meridians (0°) and the antimeridian (180°). The first one goes through the Royal Observatory in Greenwich, England, and is the origin of longitude and universal time (GMT).
El antimeridian, located at 180°, marks the so-called "International Date Line." When we cross this meridian, we change days, a key phenomenon in the world calendar. It's like the boundary between one day and the next!
Both meridians define the eastern and western hemispheres, allowing the planet to be divided into two halves for easy reference and calculation of distances or routes.
How latitude and longitude work
Latitude and longitude are the parameters that allow us to locate any point using the meridians and parallels. These coordinates are usually expressed in degrees, although they can also be expressed in minutes and seconds for greater precision.
latitude It is the angular distance between a point and the equator. It is measured in degrees (°) and can range from 0° at the equator to 90° north or south at the poles. Thus, Madrid is at about 40° north latitude.
The length It is the angular distance from a point to the Greenwich Meridian. It is measured from 0° to 180° both east and west. For example, Lima is west longitude (W), while Berlin is east longitude.
Both can be expressed as decimal coordinates or in degrees, minutes, and seconds. Locating a point is as simple as entering its exact latitude and longitude, for example, 40° 24′ N, 3° 42′ W.
The role of meridians and parallels in navigation
Cartography and navigation would not be possible without meridians and parallels.Ancient mariners were guided by the stars, but the arrival of this system revolutionized ocean voyages and continental exploration.
Today, GPS, geographic information systems, and even mobile mapping apps draw directly from this ancient knowledge.
Modern applications: GPS, digital navigation and geographic systems
Today, meridians and parallels are present in all global positioning systems (GPS), digital maps and mapping applications.When you use your phone to find an address or track a route on Google Maps, the system is constantly calculating latitude and longitude using satellite triangulation.
In geographic information systems (GIS), These lines allow us to analyze data on population, climate, land use and even distribution of natural resources.Its usefulness extends to agriculture, emergency management, and scientific research.
The WGS 84 system, used internationally in GPS, is the clearest example of the standardization and modernization that meridians and parallels have achieved.
Interesting facts and curiosities about imaginary lines
Did you know that the Greenwich Meridian determines time all over the world? In addition, there are 180 meridians on either side of Greenwich, and 90 parallels in each hemisphere. Some countries, such as Ecuador and Brazil, are crossed by the equator., while other areas enjoy unique phenomena thanks to their location within the polar circles, such as the midnight sun or the polar night.
The concept of "changing days" by crossing the antimeridian has been key to the organization of international calendars and timetables.
And in case you didn't know, The parallels also determine the climatic zones in which you live and even influence the customs and culture of each country.
How meridians and parallels are represented and used in everyday life
In practice, the representation of meridians and parallels is what you see on any globe, physical or digital map.In them, the horizontal lines correspond to the parallels and the vertical lines to the meridians.
When searching for an address or locating a point with your mobile, What is being done is projecting the geographic network onto an image to calculate distances, routes or orient the mapModern cartography has adapted traditional systems to new formats and needs, but the underlying principle remains the same.
Coordinates are still expressed in degrees, minutes, and seconds, or in decimal format, and their precision allows for locating, for example, a street, a building, or even a rock in the middle of the desert.
The imaginary lines that divide the Earth have gone from being a tool of explorers and navigators to becoming the basis of modern, connected life.From planning a trip to predicting the weather, everything relies on the invisible network of meridians and parallels that helps us find our bearings on an increasingly smaller and more accessible, yet still magical and surprising, planet.
