World Will Gain a Leap Second on Tuesday: Here's Why
Leap seconds have caused widespread problems in the past—but there's a reason we keep adding them to the world's clocks.
Time will stop on Tuesday, but only for a second. The world's timekeepers will be adding a sliver of time—a leap second—to our clocks.
Just as leap years keep our calendars lined up with Earth's revolution around the sun, leap seconds adjust for Earth's rotation. This kind of fine-tuning wasn't much of an issue before the invention of atomic clocks, whose ticks are defined by the cycling of atoms. Cesium-based clocks, one kind of atomic clock, measure the passage of time much more precisely than those based on the rotation of our planet, so adding a leap second allows astronomical time to catch up to atomic time.
It's something time scientists have done since 1972, when the first leap second
