Latitude and longitude is a coordinate system that is used for locating any
place on the globe. The first ever geo coordinate system is credited to Eratosthenes
of Cyrene and was improved upon both a Greek astronomer named Hipparchus
in the second century BC. Today it is widely used in Global positioning
systems and in geographic information systems. The earth is divided up into
horizontal lines of latitude, and vertical lines of longitude. Latitude is
read first, longitude second. Lines of latitude also known as parallels are read
in terms of north and south of the Equator. The starting point is the equator
which is 0 degrees latitude. 90 degrees north of the Equator is the North Pole.
90 degrees south of the equator is the South Pole.
Note that the poles are at a 90 degree angle from the equator. North of the
equator is the northern hemisphere. South of the Equator is the southern
hemisphere. At 23 and a half degrees north of the equator we have the Tropic of
Cancer. At 23 and 1/2 degrees south the equator we have the Tropic of Capricorn.
Between these lines of the tropics. At 66 degrees 33 minutes north and south
are the Arctic and Antarctic circles. Between here and the tropics is the
temperate zone. Lines of longitude are also known as
meridians. The starting point for reading longitude is the prime meridian which is
a line passing near the Royal Observatory in Greenwich in the United
Kingdom. This site was chosen as the international zero longitude reference
line by an international conference in 1884. The antipodal meridian of Greenwich
is both 180 degrees west and 180 degrees east. West of the prime meridian is the
western hemisphere. East of the prime meridian is the eastern hemisphere. To
locate a precise point on the earth's surface each degree of latitude and
longitude have been divided into minutes and seconds. There are 60 minutes in each
degree. Each minute is divided into 60 seconds. For example the coordinates for
the Great Pyramid of Giza as written is 29 degrees 58 minutes and 45 seconds
north, 31 degrees 8 minutes and 3 seconds east.
Now to show you how to read the coordinates of a precise point. For
example I will work out the coordinates for Mount Cook, New Zealand's highest
mountain. New Zealand is located in the southern and eastern hemispheres. The
easy part is that you can see on the map that Mount Cook is 43 degrees south and 170
degrees east. The tricky part is that between each degree of latitude or
longitude there is a division of 60 minutes. So starting with the lines of latitude,
right on the line that is 43 degrees 00 minutes. Then it goes 01 02 03 and so
on. At the halfway point it would be 30 minutes followed by 31 minutes and so on
until we get to 59 minutes before moving to the next line of latitude. We can see
that Mount Cook is located at 35 minutes. Now use the same technique to work out
the minutes of longitude. Here we get a reading off 08 minutes longitude. Thus
the full reading for Mount Cook is a coordinate of 43 degrees 35 min south, 170
degrees 8 minutes east. Now it's your turn to find the coordinates for some
famous places: How about the Great Wall of China at Mutianyu. Or the Grand Palace in
Bangkok, Thailand. Now it's your turn.