The Earth has set a new record for the shortest day.
The planet completed a full spin on 29 June 2022, in a time that was 1.59 milliseconds – little over one thousandth of a second - shorter than its standard 24-hour rotation.
It nearly broke the barrier again this month, with 26 July being 1.50 milliseconds shorter than 24 hours.
Recently, the Earth has been increasing in speed. In 2020, the Earth saw its shortest month that has ever been measured, since the 1960s. The shortest day of all time was measured that year: 1.47 milliseconds under 24 hours, on 19 July.
The next year, Earth continued to spin at a generally increased rate although did not break records.
But when looked at over much longer periods, Earth’s spin is slowing. Every century, the Earth takes a couple of milliseconds longer to complete one rotation.
The causes of this are uncertain, but scientists speculate that it could be due to processes in the inner or outer layers of the core, oceans, tides, or even changes in climate.
Some scientists have suggested that the decreased days could be related to the Chandler wobble, a small deviation in the Earth’s axis of rotation. This is similar to the quiver one sees when a spinning top starts gaining momentum or slows down, according to scientists Leonid Zotov, Christian Bizouard, and Nikolay Sidorenkov who will present at the Asia Oceania Geosciences Society next week.
If the Earth continues to spin at an increasing rate it could lead to the introduction of the negative leap second, in order to keep the rate that the Earth orbits the Sun consistent with the measurement from atomic clocks.
However, the negative leap second would potentially create issues for IT systems. Meta recently published a blog that stated the leap second “mainly benefits scientists and astronomers” but that it is a “risky practice that does more harm than good”.
This is because the clock progresses from 23:59:59 to 23:59:60 before resetting to 00:00:00 – and such a time jump crashes programmes or corrupts data due to the timestamps on the data storage.
Similarly, should a negative leap second occur, the clock will change from 23:59:58 to 00:00:00, which Meta predicts could have a “devastating effect on the software relying on timers or schedulers.”
Coordinated Universal Time (UTC), the primary time standard by which the world regulates clocks and time, has been updated with a leap second 27 times.
“We are supporting a larger community push to stop the future introduction of leap seconds and remain at the current level of 27, which we believe will be enough for the next millennium”, Meta’s engineers wrote.