The traditional song of the king of the guaracha Hannibal 'Feeling' Velasquez 'Five pa' the twelve', this year will have a 'variation', because, in reality, there will be five exact minutes to the midnight hour that marks the New Year, but for five minutes, and a second due to a compensation that will be made by the lag between the time in which they are based clocks -atomic – and the period of rotation of the Earth.
According to the agency Efe, the invention of the atomic clocks more than 50 years ago has allowed a measurement of the time "extremely" accurate. However there is another pattern in order to measure the rotation of the Earth. One and another are not always synchronized, so once in a while there is that to add a second to a day, as this December 31.
The last minute of the last day of 2016 will have 61 seconds to compensate the small variations in the length of the day that are accumulated and produce a lag between the time in which they are based clocks -atomic – and the period of rotation of the Earth, as we are reminded by Francisco Colomer, National Astronomical Observatory of Spain, not lasts precisely 24 hours, "is a approach".
The second extra is added around the world the last day of the year at 23:59:59 Coordinated Universal Time (UTC, for its acronym in English). For this reason, it is added in an extraordinary way the second 23:59:60 (that I never check) and then it switches to 00:00:00 hours, explains the expert.
In Madrid, Berlin, Paris or Rome, the official time is UTC+1h, so that such a change will occur to one in the morning of 1 January.
however, in Lisbon, London or the Canary islands, where the official time and the Coordinated Universal Time match, the change will be just in time to eat the grapes: in these sites the New Year will arrive a second later, explains to Efe Colomer.
As in all the countries that are behind the UTC time and you will see that second added at the time of the 31 of December in your schedule matches 23:59:59 UTC. That will happen, for example, at 18:00 hours in Mexico, 19:00 in New York city or 21:00 in Chile.
This second most that is added is called a "leap second" and is the International Service of the Earth’s Rotation, with headquarters in Paris, who decides and publishes on the day that you will have extra second.
This makes it thanks to the information that is sent from the different observatories, such as the National Geographic Institute (IGN) in Spain.
The earth’s rotation lasts 24 hours exact, but there are tiny variations in day length that occur because the Earth is not a rigid solid, but their rotation is affected by the coupling of the core, mantle fluid, oceans or atmosphere.
This rotation is measured daily from the telescopes of the IGN -with observations radioastronómicas with techniques of very long baseline interferometry-, which each day sends the data to the center of Paris.
When the difference between the two standards exceeds 0.9 seconds, the International Service of the Earth’s Rotation decides to remove or insert a "leap second". Has always been add, has never discounted a second, adds the astronomer of the NAO.
Colomer, who points out that there is an open debate about whether this is necessary or not, notes that the last time they added a second to the clocks was the 30 of June of last year, and the last time this happened on the 31st of December was in 2008.
In 1970, an international agreement recognized the existence of two time scales: the rotation period of the planet and the so-called Coordinated Universal Time or UTC, and at present, though the hours generated by the atomic clocks, both are necessary.
The time astronomical measures the "actual behavior of the Universe", and that is essential to, for example, space-based projects.
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