The official abbreviation for Coordinated Universal Time is UTC. This abbreviation comes as a result of the
McCarthy … See more

Time zones around the world are expressed using positive or negative offsets from UTC, as in the list of time zones by UTC offset.
The westernmost time zone uses UTC−12, being twelve hours behind UTC; the easternmo… See more

UTC divides time into days, hours, minutes, and seconds. Days are conventionally identified using the Gregorian calendar, but Julian day numbers can also be used. Each day contains 24 hours and each hour contains 6… See more

In 1928, the term Universal Time (UT) was introduced by the International Astronomical Union to refer to GMT, with the day starting at midnight. Until the 1950s, broadcast time signals were based on UT, an… See more

Earth's rotational speed is very slowly decreasing because of tidal deceleration; this increases the length of the mean solar day. The length of the SI second was calibrated on the basis of the second of ephemeris … See more

As the Earth's rotation continues to slow, positive leap seconds will be required more frequently. The long-term rate of change of LOD is approximately +1.7 ms per century. At the end of the 21st century, LOD will be roughly 86,… See more