Somewhere between the death of Leonard Cohen and that time I stubbed my toe and banged my shin on my bedframe in one fell swoop, I decided I was done with 2016. Unfortunately, hibernating in a nest of blankets and watching '90s sitcoms on Netflix doesn't pay the bills, so I've settled for willing time to go faster. You can imagine my excitement when I discovered that 2016 will last one second longer than usual, so that tactic appears to have worked out just about as well as anything else this year, i.e., not at all.
According to Science Daily, a "leap second" will be added to the world's clocks at 23 hours, 59 minutes and 59 seconds Coordinated Universal Time (UTC). In the United States, the extra second will be added to the U.S. Naval Observatory's Master Clock Facility at 6:59:59 p.m. Eastern Time (ET).
We have the Earth's rotation to blame for the existence of leap seconds. According to the National Physical Laboratory, humans have historically kept time based on the planet's rotation, but its irregularity means that the solar day kept getting longer. In 1955, two scientists invented the far more precise atomic clock, which is based on the vibration of a cesium atom. Under the atomic clock, seconds are independent of the Earth's rotation, but the International Earth Rotation and Reference Systems Service (IERS) keeps an eye on the two time scales — astronomical and atomic — to make sure there's less than a second's difference between them.
When the Earth's rotational time starts to lag too far behind, the IERS tells everyone to add a second to the year. According to the Washington Post, this takes place about every 500 days. Several different factors contribute to the irregularity of the Earth's spin, including the weight of water as it moves across the planet. Oceanic tides affect rotation in two ways: Tidal "braking," which slows Earth down, and daily variations, which produce a small but significant change in rotation.
Although it's easy to chalk this year's leap second up to the weirdness of 2016, they're more common than you might think. There have been 26 leap seconds added since they were first implemented in 1972; the last one took place on June 30, 2015. The only difference is that this year, people can't stop talking about wanting the year to be over, so the leap second is just more noticeable.
Leap seconds are important in more than just timekeeping; navigational devices like your phone's GPS depend on precise time measurements. So as much as most people just want 2017 to start already, the new year would be off to a rough start if the leap second wasn't added — although that doesn't mean you can't complain about it all night on New Year's Eve.