That’s how it is. Our planet Earth is spinning faster than it has in more than 50 years. It does it, on average, 0.5 milliseconds faster per day, which implies that each day already lasts a little less than 24 hours due to the change in the speed of the Earth that, as we have anticipated, has increased in the last five decades .
The rotation of the Earth has undergone alterations over time. And it is not something strange: the rotation of a planet varies slightly, either by ocean currents, the movement of the nucleus or atmospheric pressure.
How did they find out?
Just as dendrochronology and its observation of tree rings are used to measure the passage of time, coral also deposits a thin layer of calcium carbonate every day. And , considering that corals grow more in the dry season than in the wet season, it is possible to count the lines of calcium carbonate deposits between the seasons to determine the passage of time. It is even more accurate than looking at the rings of a tree.
Until now, the “time keepers” in charge of revising the ultra-successful atomic clocks to stipulate the Coordinated Universal Time (UTC) by which all the countries on the planet configure their clocks, had to add an extra second a year so that the clock astronomical and atomic coincided . However, now, instead of adding a second, they may have to subtract one.
This is because the average length of a day is 86,400 seconds, but an astronomical day in 2021 will be 0.05 milliseconds shorter, on average . Throughout the year, that will add to a 19 millisecond delay in atomic time. “It is very possible that a negative leap second will be needed if the Earth’s rotation rate increases further, but it is too early to say if this is likely to happen, ” National Laboratory physicist Peter Whibberley told The Telegraph of Physics of the United Kingdom.
While a ‘negative leap second’ has never been added before, a total of 27 ‘leap seconds’ have been included since the 1970s, to keep atomic time coincident with solar time.
This is because, for decades, the Earth has taken a little more than 24 hours to complete one rotation, but since last year it has taken a little less . On July 19, 2020, for example, the day was 1.4602 milliseconds shorter than the full 24 hours, the shortest day since records began.
This tiny waste of time is only detectable at the atomic level, but it has far-reaching implications.
What are its effects?
Satellites and communications equipment depend on the alignment of real time with solar time, which is determined by the positions of the stars, the moon, and the sun. It can also have an impact on all kinds of other computer systems that are not ready for change. Hence, it is so important to conclude whether it is necessary to subtract a second or not to rectify this metric disparity. It would be the first time in history that the International Earth Rotation Service would need to add a negative leap second if the Earth continues to rotate so fast in 2021.
Some scientists at the International Telecommunication Union suggest that what we need to do is let the gap between astronomical and atomic time widen until a “leap hour” needs to be added, which would minimize disruptions in telecommunications.
