View of the central portion of the Whirlpool Galaxy, M51. Credit: NASA, ESA, W. Li and A. Filippenko [University of California, Berkeley], S. Beckwith [STScI], and The Hubble Heritage Team [STScI/AURA].
What is an Atomic Clock?
The watches we wear on our wrists or the clocks we put on our walls are not atomic clocks. There are not all that many true atomic clocks - and they tend to be rather large and expensive. So, unless it looks something like the picture alongside from the National Institute for Standards and Technology [NIST], it is not a state-of-the-art atomic clock.