Much to the relief of millions of people, the United States Naval Observatory has announced that a "leap second" adjustment to everyone's clocks, watches, computers and other time keeping devices will not be necessary — "No Leap Second" will be introduced in December 2013.
The announcement was contained in Bulletin C 46 by International Earth Rotation and
Reference Systems Service as scientists and astronomers attempt to gauge
actual earth rotation vs International Atomic Time. The variance is of little
concern to the average person.
It is a very big deal to the International Space Station moving at 4.75 miles per
second and GPS satellites, in which the earth's position must correlate to the satellite.
The last leap second was in June 2012 and scientists expect another adjustment in
The earth is slowly slowing down in reaction to tides although that doesn't mean residents of planet Earth should be alarmed. The total time difference since January 1961 is 35 seconds. The adjusted time called Coordinated Universal Time.
This does not mean the day is 35 seconds shorter. It means that if you
synchronized an atomic clock to actual time of day in January 1961 to the same earth position (time of day) today, the atomic clock would be 35 seconds fast. Therefore UTC time is 35 seconds slower than atomic time.
The U.S. Naval Observatory is the official time keeper for the United States
Department of Defense, the United States Global Positioning Satellite system and the standard time for The United States.
Interestingly, the GPS uses neither UTC or TAI. It uses its own unique time. GPS
is about 16 seconds faster than UTC and is adjusted frequently to compensate for
earth rotation variations. A 4.75 mile variation is not acceptable for military and civilian GPS applications.
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