Earth has set a new record for the shortest day. According to experts, the phenomenon known as the “chandler wobble” could influence the speed of rotation of the planet.
The causes are uncertain, but scientists believe it could be due to processes in the inner or outer layers of the core, oceans, tides or even climate change.
This summer, the Earth experienced the shortest day in its history, perhaps thanks to an oscillation in its axis which caused it to complete a single rotation in a fraction of a second in less than 24 hours.
Specifically, on June 29, 2022, the planet completed a full revolution in 1.59 milliseconds less than 86,400 seconds, or exactly 24 hours, according to timeanddate.com. And this July, it was about to break the barrier: July 26 was 1.50 milliseconds less than 24 hours.
Rare Speed Boost
Recently, the Earth has increased its speed. In 2020, Earth experienced its shortest month ever measured since the 1960s. That year, July 19, the shortest day ever was measured: 1.47 milliseconds in less than 24 hours . The following year, the Earth continued to spin at a generally higher speed, although it did not break any records. Until now.
Despite occasional increases in recent times, in general, the rotation of the Earth is slowing down. Each century, the Earth takes about a few milliseconds to complete one rotation (where 1 millisecond equals 0.001 seconds).
Yet in this general pattern, the Earth’s rotation rate fluctuates. From day to day, the time required for the Earth to make a complete rotation increases or decreases by a fraction of a millisecond. Thus, in recent years, this trend has reversed and the days are getting shorter.
Why does the Earth speed up or slow down?
Although the cause of the Earth’s different rotation rates, and therefore varying day lengths, is unknown, theories abound. The most accepted is that this is due to several factors.
As Business Insider reports, the rotation we experience night and day doesn’t always occur exactly on the axis of its axis, the line between the north and south poles. Additionally, the planet has a bulge at the equator, while the poles are slightly squashed, meaning Earth is slightly elliptical.
There are also other factors that can alter the rotation, such as ocean tides and the Moon’s gravity. Similarly, there are those who point out that the melting of the glaciers causes there to be less weight in the poles, among other theories. However, some scientists point to a main, apparently more accepted reason.
Experts suggest that the reason for the trend of shorter days may have to do with the Chandler Oscillation, a small deviation from the Earth’s axis of rotation.
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 begins to gain momentum or slows down.
The wobble was first detected in the late 1880s, when astronomer Seth Carlo Chandler observed the poles wobble over a 14-month period.
“The normal amplitude of the Chandler oscillation is about three to four meters on the Earth’s surface,” Dr. Zotov told timeanddate.com, “but from 2017 to 2020 it disappeared,” said Dr. Zotov. he added.
Towards an additional negative second?
If Earth’s rapid rotation 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 step with solar time, which is based on the movement of the Sun across the sky, timeanddate.com reports.
An additional negative second would mean that our clocks would jump a second, which could create problems in computer systems.