The Leap Second: How Does It Happen, And Why Did New Year’s Day 2017 Start A Second Late?

It is now New Year’s Day 2017, and as we probably know by now, the new year has arrived one second later than it should have, due to the so-called “leap second.” And, according to reports, Earth has gained 27 seconds over the past 44 years due to this little anomaly.

The Daily Telegraph briefly went over the history of the leap second, which was first added on in 1972, and has been added 26 more times since then. In other words, everyone on Earth 44-years-old and above has gained 27 seconds over their lifetimes. That’s hardly consequential in relation to the average lifetime, but there’s more to simply adding an extra second to world times to make up for Earth spinning a bit slower than it used to.

Dr. Leon Lobo of the United Kingdom’s National Physics Laboratory told the Telegraph that most people wouldn’t have noticed the leap second when New Year’s Day 2017 hit, but these extra seconds have the potential to cause some problems. This may include events such as the ones in 2012 that caused Reddit, Foursquare, LinkedIn, and other prominent websites to crash due to the additional one second tacked on.

“People might also notice problems with mobile phone networks as they work on atomic time and, with the increased traffic on New Year’s Eve, there could be potential issues. Inserting a leap second is necessary because the Earth is wobbling and slowing down and over time that divergence could cause problems.”

A report from the Seattle Times further explained why leap seconds happen, and illustrated the difference between the two types of time we all deal with in our daily lives. The extra seconds, the report says, are decreed by the IERS (International Earth Rotation and Reference Systems Service) in Paris, which compares astronomical time against atomic time, and tracks our planet’s rotation.

As for the difference between the two types of time, astronomical time is the duration it takes for Earth to make a full rotation on its axis. It was once measured in more simplistic ways, and based on the time the sun would rise and set. But with technology having advanced as it has, astronomers now measure this type of time by tracking a distant quasar with radio telescopes. Atomic time is what is used to determine the time on your computer or mobile device, and is known as such because it relates one second to 9,192,631,770 oscillations of a cesium-133 atom – a very precise figure, but one that doesn’t always match with astronomical time.

Atomic time, due to the precise number of electron oscillations in cesium-133, is constant, but astronomical time changes as the Earth’s rotation keeps slowing down gradually. The Telegraph noted that one day lasted about 23 hours during the age of the dinosaurs, more than 65 million years ago.

But now that we’re in the present day, leap seconds are necessary in preventing the disconnect between astronomical and atomic time, correcting the latter so that it doesn’t diverge from the pace detected by Earth’s rotations. If such corrections aren’t made, the Telegraph wrote that the difference between both types of time may hit the 25-minute mark in about 500 years.

2016 marked the 27th time a leap second was added since 1972. [Image by Jessica Hromas/Getty Images]

This was a point underscored by NPL senior research scientist Peter Whibberley, who spoke to the Daily Telegraph to discuss the issue.

“Atomic clocks are more than a million times better at keeping time than the rotation of the Earth, which fluctuates unpredictably. Leap seconds are needed to prevent civil time drifting away from Earth time. Although the drift is small – taking around 1,000 years to accumulate a one-hour difference – if not corrected it would eventually result in clocks showing midday before sunrise.”

Now that New Year’s Day 2017 has come, and will be gone in any number of hours depending where in the world you’re located, what does the future hold for leap seconds? The Telegraph said that U.S. officials are opposed to them, calling these seconds “too disruptive” to navigation and communication systems, while U.K. officials want them around in order to maintain synergy between astronomical and atomic time.

Still, it may be several more years before we know what’s going to become of leap seconds, as the World Radiocommunication Conference had rescheduled a meeting to decide on the fate of these extra seconds from 2016 to 2023.

[Featured Image by Peter Macdiarmid/Getty Images]