If you thought 2008 was a long year, you had good reason to think so: it was.

A "leap second" was added to clocks worldwide to make up for slight discrepancies between atomic clocks and the rotation of the planet.

Regular time, as we know it, is established at the Greenwich Prime Meridian in England. It's all about day and night, but since the Earth rotates a bit erratically from time to time, it gets out of sync with the ultra-precise atomic clock, which ticks steadily onward regardless of what the Blue Planet is up to.

Eventually, the difference in speeds reaches nearly a second, which is when the leap second is added. The leap second is used only when needed, and has been used occasionally at the Royal Observatory at Greenwich since 1972.

The leap second keeps Greenwich Mean Time the internationally
agreed time standard, and time marches on as the world turns.