If 2020 felt like a drag, you may be surprised to discover it actually went faster than you thought … and this year is set to be even speedier.
The Earth has been spinning unusually quickly lately, and July 19 saw the shortest day since records began, with the planet completing its rotation in 1.4602 milliseconds less than the usual 86,400 seconds.
The previous shortest day in 2005 was beaten 28 times last year, and 2021 is on track to be the most nippy year ever, with the average day passing 0.5 milliseconds faster than usual.
The changes to the length of a standard day were only discovered after highly accurate atomic clocks were developed in the 1960s and compared to fixed stars in the sky.
In recent decades, Earth’s average rotational speed has consistently decreased and timekeepers have been forced to add 27 leap seconds to atomic time since the 1970s to keep clocks in sync with the slowing planet.
The last one was added on New Year’s Eve 2016, when clocks around the world paused for a second to allow the Earth’s rotation to catch up.
Then, BT’s speaking clock added a second’s pause before its third pip while Radio 4 inserted an extra pip to its 1am bulletin.
However, now the planet is speeding up and a negative leap second may soon be needed so atomic clocks can align correctly with the turning world.
It would be the first time that a second has been removed from global clocks.
Peter Whibberley, senior research scientist with National Physical Laboratory’s time and frequency group, said: “It is certainly correct that the Earth is spinning faster now than at any time in the last 50 years.
“It’s quite possible that a negative leap second will be needed if the Earth’s rotation rate increases further, but it’s too early to say if this is likely to happen.
“There are also international discussions taking place about the future of leap seconds, and it’s also possible that the need for a negative leap second might push the decision towards ending leap seconds for good.”
On Sunday, the solar day lasted just 23 hours, 59 minutes and 59.9998927 seconds, then slowed down on Monday to a little more than 24 hours.
However, in the course of 2021, atomic clocks are expected to accumulate a lag of about 19 milliseconds.
While it would take hundreds of years for the difference to become obvious to most people, modern satellite communication and navigation systems rely on time being consistent with the conventional positions of the Sun, Moon and stars.
It is the task of scientists and officials at the International Earth Rotation Service, based in Paris, to monitor the planet’s rotation and inform countries when leap seconds must be added or taken away six months in advance.
However, there can be consequences of tinkering with time.
When a leap second was added in 2012, Mozilla, Reddit, Foursquare, Yelp, LinkedIn and StumbleUpon all reported crashes and there were problems with the Linux operating system and programmes written in the programming language Java.
Some countries want to move to atomic time completely, and abolish leap second corrections, but the UK is opposed to the move because it would sever the link with solar time forever.
The World Radiocommunication Conference will decide on the fate of the leap second in 2023.
The speed of the Earth’s rotation varies constantly because of the complex motion of its molten core, oceans and atmosphere, as well as the effect of celestial bodies such as the Moon.
The friction of the tides and the change in distance between the Earth and the Moon all make for daily variations in the speed the planet rotates on its axis.
Even the snow building up on mountains and melting in the summer can shift the rotation.
Global warming will also have an effect by melting ice and snow at higher elevations, causing the Earth to spin faster, although only by a small amount.