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Do we really need a leap second?

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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 is being debated in Geneva today: 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 will see 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.

Yahoonews.

By Gaby Leslie




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