2016 is already a day longer because it is a leap year, but it appears that the year is bound to be longer than most as timekeepers announced that an extra second will be added on New Year's Eve.
The International Earth Rotation and Reference Systems Service (IERS), the body responsible for tracking and maintaining the world's time, has announced that an extra second will be added on December 31 this year.
The additional second would make New Year's celebrations last longer, as around midnight, clocks will read 11:59:60 instead of the usual 11:59:59.
Why add a leap second?
The extra time will maintain the correlation between two of the world's timekeeping systems, the measure of our planet's rotation, or UT1, and the International Atomic Time, or TAI, which uses the vibration rate of cesium atoms.
The units of time have long been based on the Earth's rotation relative to other celestial bodies, but this changed when the atomic clocks were invented in the mid-20th century. The atomic clock's invention heralded a more precise "atomic" timescale and involves a second that is independent on the rotation of the planet.
The rotation-based time loses between 1.5 and 2 milliseconds daily relative to the atomic time. This is so because the Earth's spin is being slowed down by the gravitational drag of the moon.
Other unpredictable factors, which include strong earthquakes, can also affect the length of time it takes for the Earth to rotate on its axis.
Because of this, the atomic time and the rotation-based time will have a difference of a full second every 500 to 750 days.
The IERS, which was created in 1987, may call for leap seconds to be added to make sure that the two systems stay in sync. By adding an extra second to the official time, the body makes sure that the sun is overhead at noon.
"Observations show that after roughly 500 to 750 days, the difference between Earth rotation time and atomic time would be about one second. Instead of allowing this to happen a leap second is inserted to bring the two time-scales closer together," the U.S. Naval Observatory (USNO), which maintains the Department of Defense's master clock, explained in a statement.
USNO said that while it is impossible to change the Earth's rotational speed to match the atomic clocks, changing the time of an atomic clock can be done more easily.
