All time is measured from Greenwich a
suburb of London in England.
 The zero degree longitude line or the
Prime Meridian passes through
Greenwich.
 Greenwich Mean Time (GMT) is the time
it is in Greenwich.
 Greenwich was chosen as a lot of the
world’s sea charts were being drawn up
in England at that time.

24 hours to make a complete rotation of
360 degrees
 360/24=15
 Every 15 degrees is approx 1 hour

The earth is divided into time zones.
 Each time zone has a difference in time
of approx 1 hour from Greenwich.
 Time zones tend to avoid land masses if
possible.



The line is at 180
degrees Longitude.
Time is on the same
on each side of the
line, only it is a
different day.
The earth travels west to east, hence the
west is behind the east.
 Add 1 hour for each time zone east of
Greenwich and subtract 1 hour for each
zone west of Greenwich.

Moscow
+3 = 17.00
Paris
+1=15.00
Tokyo
+9 = 23.00
Brisbane
+10=00.00
Paris
-5= 9.00
Delhi
+5.30=19.30