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Latitude and
longitude
Latitude and longitude lines are imaginary lines on the Earth used to identify places.
They are used by people who navigate ships and aeroplanes to find out where they
are and to make sure they are going in the correct direction. Any place on the Earth
can be located by giving its latitude and longitude. For instance, Newcastle upon Tyne
is 55° N, 1.5° W.
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L
a
The lines of latitude run around the
Earth. 0° latitude is the Equator, which
runs around the centre of the Earth.
The lines above and below it are
measured in degrees away from the
equator. The North Pole is at 90° north
(or 90° N).
90° N
North Pole
60° N
40° N
20° N
Equator 0°
60°
20° S
40° S
If someone on a ship at the Equator
looked up at the stars, they might see a
particular star directly overhead.
Someone standing at 40° N would see
the same star much lower in the sky.
Sailors used to find their latitude by
measuring the elevation (distance
above the horizon) of particular stars.
60° S
90° S
South Pole
Lines of longitude go from pole to pole
around the Earth. They are measured
in degrees east or west of the 0° line.
When people first started exploring the
Earth, navigators from different
countries drew the 0° line through a
place in their own country. Eventually
everyone agreed that it would be best
if everyone used the same 0° line, and
that it should run through the
observatory at Greenwich, in London.
This 0° line is sometimes known as the
Greenwich Meridian.
60° 40°
W W
20°
W
0°
20°
E
40° 60°
E E
Navigators cannot find the longitude
by measuring the stars. Before radio
and satellite navigation they needed to use a very accurate clock, called a chronometer.
The chronometer was set to the time at Greenwich. Someone on a ship would observe
the Sun to find out when it was highest in the sky, and note down the time. The
difference in time between the time they had noted down and noon at Greenwich
could be used to work out the longitude.
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Latitude and longitude (continued)
1 Which way do lines of latitude run?
2 Which way do lines of longitude run?
3 What is the Equator?
4 How did sailors find their latitude before radio navigation aids
were invented?
5 What is the Greenwich Meridian?
6 What is a chronometer?
7 How did sailors find their longitude before radio navigation aids
were invented?
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L
a
8 What are the disadvantages of the methods you have described in
questions 4 and 7?
9 Use an atlas to find out the latitude and longitude of these places:
a Edinburgh, Scotland
b Belfast, Northern Ireland
c Malta
d Cape Town, South Africa
e Easter Island
10 Find out about John Harrison and his chronometers.
S
knowledge, literacy, research
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© Pearson Education Limited 2002