The leap second: Why 2016 is going to last a little longer

The most recent leap seconds were added on June 30, 2015 and June 30, 2012.

Click Here if you’re unable to view the video above on you’re mobile device.

(KHON) – Not only did we get an extra day for the leap year, 2016 is also adding a leap second on December 31.

In modern timekeeping, this would make 2016 one of the longests years.

Timekeepers announced the additional second back in July. On Dec. 31, 2016, at 11:59 p.m. and 59 seconds Universal Time (1:59 p.m. in Hawaii), the next second will become 11:59:60. This extends 2016 by a second.

NASA explains that clocks do this to keep in sync with Earth’s rotation, which gradually slows down over time. In space, millisecond accuracy is crucial to understanding how satellites orbit.

The U.S. Naval Observatory adds that the tides’ interaction with the moon and other factors, including warmer, denser waters from El Nino, cause Earth to take longer to go full circle each day.

The most recent leap seconds were added on June 30, 2015 and June 30, 2012.

Leap seconds aren’t without controversy. In fact, the scientific community is not in agreement with some believing that leap seconds should be abolished.

According the, a decision on this topic was deferred to 2023.

If you were curious, the longest year was 46 BC, the last year of the pre-Julian Roman calendar. Julius Caesar added two extra leap months, 80 extra days, to “recalibrate” the calendar to fit his reform to align the calendar with the seasons. This resulted in a year with 445 days.

Leap Seconds: Pros and Cons from

Dr. Markus Kuhn (University of Cambridge) lists the following arguments against leap seconds:

  • Leap seconds could cause disruptions where computers are tightly synchronized with UTC.
  • Leap seconds are a rare anomaly, which is a concern for safety-critical real-time systems (e.g. air-traffic control concepts entirely based on satellite navigation).
  • Astronomical time (UT1), which is defined by Earth’s rotation, is not significant in most people’s daily lives.

His arguments in favor of leap seconds include:

  • There have been no credible reports about serious problems caused by leap seconds.
  • Some computerized systems that work with leap seconds are costly to modify (e.g. antennas that track satellites).
  • Computer errors caused by leap seconds can be avoided simply by using International Atomic Time (TAI) instead of Universal Coordinated Time (UTC).
  • Desktop computers and network servers have no trouble coping with leap seconds.
  • Humankind has defined time by the Earth’s rotation for over 5000 years – this tradition should not be given up because of unfounded worries of some air-traffic control engineers.
  • Abandoning leap seconds would make sundials obsolete.