And the answer is a clock," said Warren Walls of the U.S. Naval Observatory. ... "We have over 100 different atomic clocks that we use to generate our realization of UTC.

Looking for an atomic clock on Earth? The Naval Observatory in Washington, D.C. is full of them. Bettmann/Bettmann/Getty Images. What is an atomic clock? Invented back in 1948, ...

This timekeeping device is based on a ytterbium lattice that combines two atomic clocks, ... Times labeled UT in astronomical almanacs such as those produced by the U.S. Naval Observatory are UT1.

The atomic clock is a standardized unit of measurement that has been used since the 1950s to tell time and measure the Earth’s ... retired director of time at the US Naval Observatory. ...

Interestingly enough, even though the U.S. Naval Observatory in Washington D.C. is the other partner in the timekeeping business and the primary location of its clocks is in the nation’s capital ...

The planet’s rotation was completed 1.59 milliseconds short of a 24-hour day on June 29, breaking the record for the world’s shortest day in modern history.