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Don't
Forget! British Summer Time comes to an end this weekend (2003).
Remember to put your clocks BACK one hour before you go to bed on
Saturday night.
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| Greenwich
Mean Time is no longer used |
If
you are really keen to get the time just right, you can stay up
until 1 am on Sunday and make the change then.
At
that time, we will change not to Greenwich Mean Time but to Universal
Time. Greenwich Mean Time was a scale of time measurement based
on the apparent motion of the 'mean' Sun with respect to the 0 degrees
line of longitude, the meridian, based at the Old Observatory at
Greenwich.
Unfortunately
the orbit of the Earth around the Sun is 'eccentric'. In other words
it is variable. This is far from ideal when we are seeking a constant
way of measuring time.
As
long ago as 1925 the International Astronomical Union was proposing
a form of Universal Time, one which was less affected by the variations
in the eccentricities of the Earth's orbit.
By
the 1960s the new scale was based on atomic time, using emissions
from caesium atoms as its point of reference. The scale is now known
as Coordinated Universal Time and has become more widely accepted
than GMT.
Whatever
you call the change in clock time, remember to make the most of
that extra hour.
by
Richard Angwin
If
you would like to comment on this or any other story in this section then get
in touch at gloucestershire
@bbc.co.uk
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