Earth is spinning faster, and 2020 had the shortest day in 50 years. Hold on tight, for the first time in last 50 years, it may be necessary to add (not remove) one second to atomic clocks to be aligned with the Earth’s rotation. July 19 was the fastest day since 1970.
The actual length of days depends on the speed of the Earth’s rotation about its next axis.
Amid the eventful events that marked last year, there was one that was so tenuous that it escaped the most vigilant wristwatches. July 19, 2020, was the shortest recorded over the previous five decades: it had 1.4602 milliseconds less than the usual 86,400 seconds that make up the 24 hours of a day. And this year, the days are getting even smaller, with 1.5 milliseconds less than expected.
It was because the Earth is spinning faster on its axis. Nothing that should frighten humanity: since atomic clocks were invented in the 1960s, scientists have known that the rotation of the planet varies with the tides, the gravitational effect of the Moon, the erosion of mountains and catastrophic phenomena such as earthquakes, tsunamis, hurricanes and volcanic eruptions.
That is why, from time to time, for our measurement of time to match the speed of the Earth’s rotation, an extra second – the leap second – is added to Coordinated Universal Time (UTC). Since 1970 until now, this has happened 27 times, the last of which was on New Year’s Eve from 2015 to 2016. The whole world waited for a second to celebrate the New Year’s entrance and align the clocks with the planet.
2020 Brought a Surprise (yes, another)
The rotation of the planet began to accelerate to the point that, throughout this year, atomic clocks could accumulate 19 milliseconds of delay concerning the actual movement of the Earth around itself. If this is confirmed, it may be necessary to take time off clocks, which has never happened in 50 years of atomic time measurement.
The decision will be made by the International Earth Reference and Rotation Systems Service, in Paris, France, which monitors the passage of time using 260 atomic clocks scattered across the planet. The addition of a leap second is unpredictable and depends on a committee’s calculations, which meets in the middle and at the end of each year. If the scientists decide to move forward, the second is added six months later, on June 30 or December 31.
But even if no one touches the clocks, it can take hundreds of years for earthlings to notice a noticeable gap between our measurement of the Earth and the movement of the Earth. It has been debated whether this Service is so central. The European Space Agency (ESA) even considered this adjustment a “danger to navigation” in 2014. But the discussion has been on since 2005 and the Service remains active.
For the technological world, for example, this adjustment is less comfortable. Since satellites and some computers rely on atomic clock time to function, errors can be reported because of these adjustments. In 2012, when a second leap was added, companies such as Linux, LinkedIn, Mozilla and Qantas reported malfunctions until they were adjusted according to the new time.