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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 seconds 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 Earths rotation) in sync with each other. 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 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 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. Thursday 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 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 debate, which an ITU-R spokesperson described as very polarised could see all that change. 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. 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 spokeswoman |
Science explained: What is a leap second?
But what is a leap second? Why do some people want to get rid of it? And what would happen if we do?
Science reporter Rebecca Morelle heads to the Royal Observatory, Greenwich, to explain.
http://www.nidokidos.org/threads/170064-Science-explained-What-is-a-leap-second
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