What is atomic standard time based on?

Atomic standard time is based on periodic vibrations produced in an atom, specifically the oscillations of atoms that resonate at very precise frequencies. This concept is rooted in the understanding of atomic clocks, which measure time by counting the vibrations of atoms, often cesium or rubidium. These vibrations are incredibly stable and can be used to define the second with great accuracy, making atomic timekeeping far more precise than timekeeping methods based on celestial events or solar time.

In contrast, other methods of measuring time, such as those related to celestial events, follow the regularity of phenomena like the Earth's rotation or its orbit around the sun. However, these methods can be affected by irregularities in the Earth's motion. Moreover, standard time zones are geographical divisions of the world that define local time but do not provide the accuracy of atomic time. Similarly, the orbital positions of planets involve dynamic and varying distances that do not lend themselves to a stable timekeeping system. Thus, the reliance on the atomic vibrations ensures a much higher degree of consistency and precision, making it the foundation for atomic standard time.