The
Royal Observatory in Greenwich, England, is debating whether to alter the way it measures time.
From the article:
Rory McEvoy, curator of horology at the UK's Royal Observatory in Greenwich, explained: "Since the 1920s, it has been known, and previously suspected, that the motion of the Earth is not quite as constant as we'd first thought."
Only one man can help us now.

Thank you for information; this may be a fun read:
At the centre of time Without it international travel would be in turmoil and calling friends in faraway places at the right time impossible. Exactly 125 years after the Greenwich Meridian line was drawn, how and why did Britain become the centre of time?
http://news.bbc.co.uk/2/hi/uk_news/magazine/8266883.stm Opinions?
The reason for this is that while atomic clocks, which use the vibrations in atoms to count the seconds, are incredibly accurate, the Earth is not such a reliable time-keeper thanks to a slight wobble as it spins on its axis.

Atomic clocks are much better at keeping time than the Earth