We have all heard a leap year - that additional days added to the calendar every four years. It can give us a longer February but it is also important to fit in perfectly with our calendars and seasons. If the additional days was not a leap year then eventually (albeit after more than a century) the Winter will begin in July and will begin in the summer, at Christmas (and vice - versa) in the southern hemisphere, because the earth is an additional six takes hours longer than 365 days a year toCircle of the sun.
A leap year can be a bit of fudge but the alternative, fourth day have at the end of the year, not what our days and nights would of course throw in sync with each other (and you might imagine, with only six hours a day - some of us fight, to do things in 24!).
Of course we have always measured time in relation to the movement of the earth - one day will be a complete revolution, a year in orbit the sun. However, as our way of measuring time became more and more it soon became apparent that there are other irregularities in the rotation of the earth than the additional six hours in a year.
GMT (Greenwich Mean Time) was developed because there is a need for a time scale where the mean position of the sun at noon, averaged over the whole year on the Greenwich Meridian (zero longitude) and summer time hours are added or removed depending on the time of the year.
But in 1955 the first atomic bomb> Clock went into operation after the discovery of the stability of the cesium-133 atom) at an exact phrase vibrated (9,192,631,770 a second. With this accuracy, adopted the International System of units (SI) that a second, should be defined as the number of oscillations of the cesium-133 atom.
According to the SI second a time scale as International Atomic Time (TAI - from the French Temp Atomique International), include a simple, wasSeconds for the 24 hours of our time. Conversely, as TAI were not related to the movement of the earth, it was soon discovered that TAI and atomic clocks were far more stable and reliable than the Earth itself (in fact, an atomic clock is 1000000 times more accurate than the Earth) rotation.
In general, the earth is always slower (in their rotation, though for no apparent reason and then it seems to accelerate), the TAI is of little use for those who want theirClocks to be in harmony with the earth (astronomers, which) are by far most of these songs.
Thus, another time scale has been developed called Coordinated Universal Time (UTC - again from the French - Temp Universel coordonné). This was on Atomic Time (TAI), but are made small adjustments to make it in line with the GMT-based ( by the way, now commonly referred to as UT1, or depending on the time zone, UT 1 UT 2 UT 3, etc.)
UTC is adjusted by the insertion of extra seconds, as the jumpSeconds, as necessary, keeping to within one second of GMT (or UT1). It is possible, a second must be removed in the future under certain circumstances, but it has not happened until now. Clock in modern industry is very important in computer technology and the UTC-synchronized time, usually by using an NTP server (Network Time Protocol) - the type of time sensitive international transactions.
A leap seconds is usually inserted at the end of December in the last hour (although it was sometimes in June, done in Marchand September). In deciding whether a leap second is necessary, is taken from the Earth Orientation Center of the International Earth Rotation and Reference Systems Service (IERS), which can monitor the Earth's rotation and the adjustment of six months in advance.
If a leap second is added 61 seconds in the final minute of the year. The well-known "six pips" radio signal, will receive an additional pip and even London's famous Big Ben held back before a second bongs (butNo additional bong how they intended to represent the hours) are
There have been 33 leap seconds have been added to UTC since 1972 (when the first ones were added later to ten), but as the earth's rotation is continuing to slow it is estimated that over the next thousand years or have two leap seconds will be added each month.
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