Latitude and longitude
With latitude (north or south of the equator) and longitude (east or west of Greenwich) you give every place on earth its own address.
Why
A lifeguard on the beach at De Panne hears on the radio that a small boat is in trouble. How do you say exactly where that boat is, out at sea, with no streets or house numbers?
At sea, in a desert or in a big forest there are no addresses. Yet a rescuer, a pilot or a captain has to know exactly where something is.
For that, an imaginary grid lies over the earth: the lines of latitude and longitude. Two numbers are enough to point to any place.
See it
Slide the latitude and the longitude and see where the point lands on the globe. The globe turns along, so you always see the point at the front.
Description of the picture
A globe with a grid of lines every 15°. The equator and the prime meridian through Greenwich are drawn thicker. Brussels lies at about 50.8°N and 4.4°E.
Get it
Lines of latitude, or parallels, are circles parallel to the equator. The equator is 0°. Towards the poles it rises to 90°N at the North Pole and 90°S at the South Pole.
Lines of longitude, or meridians, run from pole to pole. The prime meridian runs through Greenwich near London and is 0°. From there you count up to 180° east and up to 180° west.
You give a place with two numbers: first the latitude, then the longitude. Brussels lies at about 50.8°N and 4.4°E: north of the equator and east of Greenwich.
Two parallels 1° apart are about 111 km apart everywhere. That is how you work out distances from north to south.
Latitude: from 0° to 90°, north or south of the equator. Longitude: from 0° to 180°, east or west of Greenwich. From north to south, 1° is about 111 km.
Worked example
A boat sails from 51°N straight south to 48°N. About how many kilometres is that?
The difference in latitude:
51−
48= 3 Each degree is about 111 km.
3×
111= 333 - Answer
The boat sails about 333 km.
Do it
Choose a level. You get a new exercise every time, checked straight away.
Pitfalls
Wrong: Brussels lies at 4°N and 51°E.
First comes the latitude, north or south, then the longitude, east or west. The letter belongs to the number before it.
Right: Brussels lies at about 51°N and 4°E.
Wrong: Between two lines of longitude there are also 111 km everywhere.
The meridians meet at the poles. The closer to a pole, the smaller the distance between two meridians.
Right: Only between two lines of latitude is it about 111 km everywhere.
Wrong: The equator is 90°, because it lies in the middle.
Latitude is counted from the equator, northwards and southwards.
Right: The equator is 0°, the poles are 90°N and 90°S.
In real life
- When you share your location on your phone, it actually sends two numbers: your latitude and your longitude.
- On a sea chart of the North Sea off Ostend, the lines of latitude and longitude are marked along the edge.
- In the school atlas you look up a city using the grid of latitude and longitude.
- The 50°N line of latitude runs through the south of Belgium, through the Ardennes.
History
In 1884, countries at a conference in Washington agreed that the prime meridian would run through Greenwich near London. That is how Greenwich became the place of 0° longitude.
At the table
Look up the latitude and longitude of your home together in a map app. Is it north or south of 51°N?
A question to talk about together, for parents and children. There is no wrong answer.