International Atomic Time, Universal Time: What is it ?
UTC time, International Atomic Time, or Universal Time, You don't know what the difference is? Don't worry, we'll explain their roles and characteristics.
UTC time, atomic time and universal time
UTC is the global reference time and stands for "Coordinated Universal Time." It is a time scale determined, among other things, by some 500 atomic clocks located in 70 laboratories worldwide. UTC was adopted in 1972 to uniformly define international civil time. UTC replaced Greenwich Mean Time in 1982, but UTC+0 still corresponds to the time in the Greenwich Mean Time Zone. The time within each time zone is therefore defined relative to UTC. UTC is actually a combination of International Atomic Time (TAI) and Universal Time (UT).
UTC possesses the stability and accuracy of TAI to within a whole number of seconds, allowing it to approach UTC. The difference is fixed at less than 0.9 seconds. To maintain this delicate balance, UTC has a whole atomic second, also called a leap second, added or subtracted at the end of June or December. Before the adoption of UTC, GMT, or "Greenwich Mean Time," was used. This is mean solar time at the prime meridian of longitude. This meridian passes through the Royal Observatory Greenwich near London.
International Atomic Time
International Atomic Time is a time scale relative to the duration of one second. It was determined in 1967 by the 13thth General Conference on Weights and Measures that a second would be " equivalent to the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom To put it simply : A Cesium 133 atom receives a frequency of 9 192 631 770 Hz which allows This allows the atom to change its energy state. The time that elapses between the F3 and F4 energy states of the cesium-133 atom is exactly one second. The advantage of the atomic clock is its exceptional precision. : It drifts by less than one second every 30 million years. Researchers have even developed a strontium atomic clock with an accuracy of less than one second every 15 billion years! Regarding the operation of an atomic clock, it uses the frequency of electromagnetic radiation emitted by an electron when transitioning from one energy level to another. The atomic clock ensures the accuracy and stability of the signal it produces. The atomic clock defines a time standard, called the second. The TAI (Time Atomic Intensity) is calculated by the International Bureau of Weights and Measures. It corresponds to the average of 500 atomic clocks located around the globe. However, the TAI is not used as is because it does not take into account the Earth's rotation time in a day.
What is the role of Universal Time in defining UTC time?
Universal Time, or UT, is an improved version of Greenwich Mean Time. UT is also a measure of time, except that it is not an atomic measurement but a measurement relative to the Earth's rotation on its axis (which takes 24 hours). The problem is that the Earth's rotation is not very regular; it may slow down due to the effects of tides, earthquakes, or other internal disturbances within the Earth (even if this delay remains minimal).UTC is a combination of these two times, calculated so that the sun is at the Greenwich meridian within 0.9 seconds at 12:00 UTC. The second in UTC is the same as the second given by TAI. However, to find UTC, whole seconds are subtracted or added to TAI so that the difference between TAI and UTC is less than 0.9 seconds.
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