In this article we tell you everything you need to know about coordinates on a map. We start by defining and visualizing basic concepts such as geographic coordinates, parallels, meridians, latitude and longitude.

Once these terms have been clarified, we will explain how to calculate coordinates on a map. In addition, we leave you several examples so that you can clarify all your doubts.

## What are geographic coordinates and what are they for?

Geographic coordinates are a system that allows detailing the location of any point on the Earth’s surface based on two angular coordinates, latitude (north or south) and longitude (east or west).

What it is about is **measure lateral angles from the center of the Earth to a point on the Earth’s surface**.

** ****Geographical coordinates**

** **

To visualize what geographical coordinates are, we can think about **a grid on the earth’s surface** which is formed from imaginary lines.

By gridding the globe it becomes much more accessible for us to locate a certain point on the surface of planet Earth.

Imaginary lines are of two kinds, the first we call **parallels **and they help us to measure **the latitude**.

We name the second ones as **meridians **and are useful for measuring **the length**.

**Planet Earth on a grid**

** **

Let’s see below how parallels, meridians, altitude and longitude are defined.

### The Parallels

To talk about the **parallels **we have to refer to **equator which is the largest of the imaginary circles**. This circle is at the same distance from the poles. It is characterized by forming a 90º angle with the Earth’s axis of rotation and separating our planet into two hemispheres: the Northern hemisphere and the Southern hemisphere.

** **

**The equator of planet Earth**

Graphically, the Northern Hemisphere is a semisphere that goes from the equator to the North Pole, while the South Pole is the other semisphere that begins at the equator and ends at the South Pole.

From north to south we can draw imaginary parallel circles to the equator. As these circles approach the poles they become smaller. Each of these smaller circles is called parallels.

**The equator is recognized as the 0º parallel**, and as we have already said, it is responsible for dividing our planet into two halves. The parallels are numbered from 0º at the equator to 90º at the South Pole and 90º at the North Pole.

There are 4 parallels that are of great importance because they delimit the climatic zones of planet Earth. They are: The Tropic of Cancer, the Tropic of Capricorn, the Arctic Circle and the Antarctic Circle.

The Arctic Circle (66° 33′ N) is in the Northern Hemisphere and the Antarctic Circle (66° 33′ S) is in the Southern Hemisphere.

These parallels record the points located furthest south and north of the equator. In these coordinates it happens that on certain dates the sun does not rise or disappear on the horizon.

The Tropic of Capricorn (23° 27′ S) is located in the Southern Hemisphere and the Tropic of Cancer (23° 27′ N) is located in the Northern Hemisphere. Its function is to indicate the southernmost and northernmost points of the equator where the sun’s rays fall vertically.

*Taken from: la Verdadnoticias*

** **

### The Meridians

Meridians are circles perpendicular to the equator that intersect the poles of the Earth.

Each meridian is made up of two semicircles, one that contains the selected meridian and another that defines the opposite meridian (antimeridian).

** **

*Taken from: topographic engineering*

There is a very important meridian called **Greenwich meridian or 0º meridian**. It is responsible for dividing planet Earth into two hemispheres. The first is the Western hemisphere or Western hemisphere and the second is the Eastern hemisphere or Eastern hemisphere.

The Greenwich meridian is used as a reference for establishing time zones.

### Latitude and longitude

Now that we know what parallels and meridians are, we are ready to know that any surface on planet Earth can be referenced from the intersection of these two lines. The point at which they intersect corresponds to some region of the Earth. It is from these ideas that the concepts of latitude and longitude arise.

Latitude gives us the location of a site, in the North or South direction starting from the equator.

The unit of measurement in which latitude is expressed is angular. The values taken by latitude range from 0º from the equator to 90º from the North Pole or from 0º from the equator to 90º from the South Pole.

**Latitude on globe. Reference image**

When expressing the measurement of latitude in degrees, the hemisphere to which it belongs must be indicated or a positive sign (+) must be added in the case of the North and a negative sign (-) if it is the South.

For example, 20º North latitude can be written as 20º N or +20º, while 20º South latitude would be expressed as 20º S or -20º.

In the image we can see that the angle ** b**whose sides are the segment

**O.A.**(on the equatorial plane) and the segment

**OC**expresses the latitude at the point

**c**. Point

**TO**It is located in the Northern Hemisphere.

### Length

Longitude is responsible for giving us the location of a place, in an East or West direction starting from the Greenwich meridian.

Its measurements are expressed in angles ranging from 0º to 180º in the East direction and 0º to 180º in the West direction.

When we want to express the measurement of longitude in degrees we must indicate the hemisphere to which it belongs or add a positive sign (+) in the case of the East and a negative sign (-) if it is the West.

For example, 10º West longitude can be written as 10º **AND** or +10º, while 10º of West longitude would be expressed as 10º **EITHER** or -10º

In the image it is observed that the angle ** and** It measures the angular distance between the meridian containing point C and the Greenwich meridian.

It is important to keep in mind that it is the same to measure this angle on the circumference of the equator as on the circumference of the parallel that passes through point C, in both cases the measurement of the angle** and** it’s the same.

In this example, the longitude is East (E) since the meridian of the point **c **It is east of the Greenwich meridian.

## How to calculate the coordinates of a point on a map

To calculate the coordinates of any point on a map we must return to what the latitude and longitude of a point mean, since both constitute the coordinates of that point.

Remember that the **latitude** It refers to the **vertical coordinate**, and is the distance between the parallel of a point and the equator. It is measured in degrees, from 0° to 90° towards North or from 0° to 90° towards South.

And the **Length** is the **horizontal coordinate**, defined as the distance between the meridian of a point and the Greenwich meridian. It is expressed in degrees, minutes and seconds of arc, and is measured from 0° to 180° towards the East or from 0° to 180° towards the West.

With this clear, let’s see how to calculate the coordinates of point A that we have marked on the map.

To know **the latitude of A** we have marked **the parallel in red** on which the point is **TO** and we lengthen it until we reach the measurements in degrees that the map has. In this case, we see that **Point A has latitude 10° North**.

To determine **the length of point A** we look at the **meridian** in which it is located. In this case **we have highlighted it with blue color** until reaching its measurement, which is 70° towards the West. We then say that **Point A has Longitude 70° West**.

The approximate coordinates of the **point a **are: **10°N 70°W**

They can also be written like this: **Lat 10°N Long 70°W**

**These are the approximate coordinates of a city in Venezuela called Carora**.

Let’s look at another example of how to calculate the coordinates of a point on a map. Look at the location of point B on this map:

To determine **the latitude of the point** **b**we highlight in **red **the parallel on which it is located. This allows us to place the measurement in degrees. We see that **the latitude of B is 20° North**.

As with the previous point, to know the **length of point B** We look at the meridian on which the point is. But in this case it is not found in any of the meridians, so we draw in **blue** a straight line parallel to the Greenwich Meridian to the measurements in degrees on the map.

**The longitude of B is approximately 103° West**. We can tell this because it is between 100° and 110°, below the midpoint between the two.

The approximate coordinates of the **point B** are: **20°N 103°W**

They can also be written like this:** The t** **20°N Long 103°W**

## How to look at coordinates on a map

In this section of the article we will see how, having the coordinates of a given point, we can determine the location of that point on the map. That is, we will learn how to look at coordinates on a map.

**Let’s say we have the following coordinates:**

To know where this point is located on the map, we are going to work with the parallels and meridians. Let’s see:

We locate the **parallel 50°** North and the **meridian 10° East**. We highlight the parallel that they indicate to us, and we do the same with the meridian. In this case we use red and blue, respectively.

Now we mark the point exactly in the place where the lines we have drawn intersect, or “cut”,.

**These are the approximate coordinates of the German city of Arnstein.**

**Let’s now see how to locate this point on the map:**

First we are going to locate the parallel and the meridian that the coordinates indicate to us to highlight them and see where they intersect.

Now we place the point we are looking for at the intersection of both lines.

**These are the approximate coordinates of the city of Dongola in Sudan.**

## Geographic coordinates examples

In this section we will see three examples of geographic coordinates on a map.

**They give us the following map on which points A, B and C have been marked:**

Let’s determine its coordinates. To do this, we will highlight** parallels and meridians** on which each point is located. Remember that we do this to read the corresponding coordinate on the edge of the map.

Let’s see what coordinates each point has:

**Point a**

Latitude 60° North and longitude 120° West. That is, 60°N 120°W. These are the approximate coordinates of the northernmost point of the border between the Canadian states of Alberta and British Columbia.

**Point B**

Latitude 40° North and longitude 0°. That is, 40°N 0°E. These are the approximate coordinates of the Meridiano Park in Castellón, Spain.

**Point C**

Latitude 30° South and longitude 150° East. That is, 30°S 150°E. These are the approximate coordinates of Couradda New South Wales, Australia.

*Below we leave you some resources so you can practice:*

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Definition of coordinates

Hemispheres

Earth parallels

Earth meridians

Latitude and longitude

Coordinates of a point