If you have a 9 to 5 work schedule, your workday will be a bit longer on Tuesday -- but not by much. It doesn’t have anything to do with more work, but rather the Earth’s rotation.
When clocks reach 4:59:59 in the evening, the next second usually reads 5:00:00. But at 4:59:59 p.m. Tuesday, the next second will be 4:50:60, then 5:00:00, extending today, and many Arizona residents’ workday, by one second.
This isn’t an attempt to keep people at work as much as it is a coincidence that 4:59 p.m. Pacific Standard time is the same as 11:59 p.m. Coordinated Universal Time, formerly known as Greenwich Mean time. The world’s clocks need to keep pace with the Earth’s rotation, which is slowing at about 1 to 2 milliseconds per day. Because of this, we periodically need to add a leap second to allow the Earth’s rotation to catch up to our clocks.
The last leap second occurred on this day three years ago.
