Everyone knows what a leap year is, but did you know there are also leap seconds?
At least for now, because the leap second’s very existence was debated in Geneva Yesterday:
with Britain, China and Canada fighting to keep it against the USA, Germany and France.
Introduced globally 40 years ago, the leap second was designed to keep atomic time
(used by computer systems) and astronomical or solar time (the Earth’s rotation) in sync with each other.
Discrepancy
Atomic time, which GPS and telecommunications depend on,
is so accurate that it gains or loses no more than a second every million years.
However, astronomical time alters because of variations in the Earth’s rotation and can be affected
by things like earthquakes. The leap second was needed to keep the two time scales coordinated
so atomic time doesn't jump ahead of astronomical time, the International Telecommunication’s
Union (ITU-R) explained to Yahoo! News.
In fact, a leap second has been added at irregular intervals – a total of 24 times since
its introduction in 1972.
Without the leap second keeping time in check, it is predicted that the difference between
atomic time and astronomical time will increase at a rate of approximately one second per year –
meaning that in 550 years, the difference between atomic time and astronomical time will be
about an hour, the International Bureau of Weights and Measures (BIPM) projects.
The decision
Thursday’s Radiotelecommunication Assembly saw delegates from member states discuss the
elimination of the leap second and voting for or against the controversial proposal.
A decision to remove the leap second completely would then need to be approved at the
ITU-R’s World Radiocommunication Conference due to take place next week.
The next leap second is expected to be added at midnight on 30 June. However,
Thursday’s debate, which an ITU-R spokesperson described as “very polarised” could see all that change.
Against the leap second
Countries like France, Italy, Germany and the USA are calling for an end to the leap second
because telecommunications from GPS systems to mobile phone networks must be manually
adjusted by a whole second to keep in sync with the change every year or two.
This adaptation of a second, critics argue, leaves systems open to the risk of error.
If the leap second was abolished, time would be more standard.
The ITU-R, a United Nations agency, said in a statement:
“The benefits of the change would be a continuous time scale available for all the modern electronic navigation
and computerised systems to operate with and eliminate the need for specialised ad hoc time systems.”
For the leap second
Britain, China and Canada are opposed to the change because without that leap second,
atomic and astronomical time will drift further apart, which would need to be corrected by
adding a single leap second, minute or hour at an agreed point in time which would be
even more technically challenging and costly.
“Without leap seconds we will eventually lose the link between our perception of time
and our own experiences of day and night,” added the ITU-R’s spokeswoman
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