What is the International Atomic Time (TAI), and how does it differ from Coordinated Universal Time?
What is the International Atomic Time (TAI), and how does it differ from Coordinated Universal Time?
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International Atomic Time is a high-precision time standard based on the measurements of more than 300 atomic clocks located in more than 60 metrology institutes and observatories around the world. These atomic clocks use the vibrations of atoms to keep time with extreme accuracy, thereby providing a much more consistent measure of time than methods based on the rotation of our planet or its revolution around the sun.

Coordinated Universal Time is the time standard used in aviation, computing, navigation, weather forecasting, and many other fields. Unlike TAI, which is purely atomic in nature, UTC is closely aligned with mean solar time (a modern replacement for Greenwich Mean Time) and accounts for variations in Earth's rotational speed by occasionally introducing "leap seconds". While TAI ticks away uniformly, the Earth's rotation gradually slows down over time. This means that UTC, which is pegged to the Earth's rotation, occasionally falls out of sync with TAI. To correct this, a "leap second" is added to UTC approximately every 18 months, although the exact timing is determined by the International Earth Rotation and Reference Systems Service (IERS). 
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