Wait a Second
Everyone has heard of leap years. They usually occur every four years. But have you ever heard of a leap second?
Most genealogists who have traced their family back beyond 1800 have come across the concept of the Gregorian calendar, which is used by most of the world today. It replaced the Julian calendar because the Julian calendar was not accurate at calculating leap years (see Understanding Julian Calendars and Gregorian Calendars in Genealogy). It turns out the Gregorian calendar is not 100% accurate either.
The International Earth Rotation and Reference Systems Service is the body responsible for calibrating clocks and calendars around the world. They introduced the concept of leap seconds in 1971 to reconcile changes in the length of the Earth’s year. Leap seconds are not added every year; the last one was added in 2005. One will also be added at the end of 2008, making 2008 officially one second longer than 2007. You can read the official announcement here.
So when celebrating the New Year on December 31, 2008, wait a second.
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