The year 2017 isn’t coming as soon as you think. In fact, it will be exactly one second late.
On Dec. 31, 2016, the international time keeping community will tack an additional second, known as a leap second, on to the last minute of the year.
As midnight approaches, the official atomic clocks that keep Universal Coordinated Time will mark the time as 23h 59m 59s, followed by the leap second 23h 59m 60s. Jan 1 will continue as usual, beginning with 0h 0m 0s.
Unlike leap years, leap seconds are not a regular occurrence. Instead, they are decreed by the International Earth Rotation and Reference Systems Service, or IERS, in Paris, which measures the Earth's rotation and compares it with the time kept by atomic clocks.
More at LA Times.