This summer, the Earth had the shortest day in its history, possibly thanks to a wobble on its axis that made it complete a single turn in a fraction of a second less than 24 hours.
Specifically, the 29 June 2022, the planet completed a full turn in 1.59 milliseconds less than 86,400 seconds, that is, exactly 24 hours, according to the website timeanddate.com . And this July he was about to overcome the barrier: the 26 July was 1.50 milliseconds shorter than 24 hours.
Rare increase in speed on Earth
Recently, the Earth has increased its speed. In 2020, Earth saw its shortest month ever measured since the decade of 1960. That year, on July , the shortest day of all time was measured: 1.47 milliseconds less than 24 hours. The following year, the Earth continued to rotate at a generally higher speed, although it did not break records. Until now.
Despite the occasional increases in recent times, in general, the rotation of the Earth slows down. Every century, the Earth takes a couple of milliseconds or so to complete one rotation (where 1 millisecond equals 0).001 seconds).
Still, within this general pattern, the Earth’s spin rate fluctuates. From day to day, the time it takes for the Earth to complete one rotation increases or decreases by a fraction of a millisecond. Thus, in recent years, this trend has been reversed and the days are getting shorter.
Why is the Earth speeding up or slowing down?
Although the cause of the different speeds of rotation of the Earth, and therefore the variable duration of the days, is unknown, theories abound. The most accepted is that this is due to several factors.
According to Business Insider, the turn we experience as night and day does not always occur exactly in line with its axis, the line between the north and south poles. Also, the planet has a bulge at the equator, while the poles are slightly squashed, meaning the Earth is slightly elliptical.
There are also other factors that can alter the rotation, such as ocean tides and the Moon’s gravity. In the same way, there are those who point out that the melting of the glaciers causes that there is less weight in the poles, among other theories. However, there are scientists who point to a main reason, apparently more accepted.
The Chandler wobble
Experts suggest that the reason for the trend of shorter days could be related to the Chandler wobble , a small deviation in the axis of rotation of the Earth.
According to scientists Leonid Zotov, Christian Bizouard and Nikolay Sidorenkov, who will present the hypothesis this week at the Asia-Oceania Society of Geosciences, this phenomenon is similar to the tremor observed when a spinning top starts to gain momentum or slow down.
The wobble was detected for the first time once in the late 550 decade, when astronomer Seth Carlo Chandler observed that the poles they wobbled for a period of months.
“The normal amplitude of the Chandler wobble is about three or four meters at the surface of the Earth,” Dr. Zotov told timeanddate.com, “but from 1960 to 2020 disappeared”, he added.
Towards an additional negative second?
If the rapid rotation of the Earth continues, it could lead to the introduction of the first additional negative second in history.
This would be necessary to keep civil time – which is based on the super-stable rhythm of atomic clocks – in tune with solar time, which is based on the movement of the Sun across the sky, according to reports timeanddate.com.
2022
An additional negative second would mean that our clocks would skip a second, which could create problems in computer systems. 2025
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