Tom muses about that hour-and-a-half disconnect between what's happening with Cassini at Saturn and reception of the signal on Earth.
Meanwhile, I'm sitting in a cottage in the west of Ireland setting my computer's clock with official U. S. Government time broadcast on the internet.
It takes less than a fifth of a second for a radio signal to go right around the Earth. Of course, the info displayed on the government's time site gets bounced all over the place in packets of binary data before it reaches my computer. Accurate to within 0.7 seconds, says Uncle Sam.
The signal is generated with atomic clocks by the National Institute of Standards and Technology and the U. S. Naval Observatory in Washington. These institutions contribute to something called Coordinated Universal Time (UTC), from which their clocks never deviate by more than 0.0000001 seconds.
What's now? asks Tom. UTC, that's now.
(So why is the acronym for Coordinated Universal Time UTC, rather than CUT? A compromise with the French Temps Universel Coordonne, TUC.)