Time is flying by – global clocks may soon need to be sped up to match the Earth’s slower rotation

If it feels like there’s never enough time in the day, there may be a reason.

arth had its shortest day on record last month, slacking 1.59 milliseconds from the usual 24-hour rotation on June 29 – raising the prospect that a negative leap second may soon be needed to keep the clocks moving to align with the sky.

Normally, the Earth’s average rate of rotation decreases slightly over time, and timekeepers have been forced to add 27 leap seconds to atomic time since the 1970s as the planet slows.

But since 2020, the phenomenon has reversed, with records frequently broken over the past two years.

The previous fastest day was 1.47 milliseconds under 24 hours on July 19, 2020, almost breaking again on July 26 when the day was 1.50 milliseconds shorter.

Although the effect is too small for humans to notice, it can accumulate over time, potentially affecting modern satellite communications and navigation systems that rely on time to coincide with the conventional positions of the sun, moon, and stars .

This means that it may soon be necessary to remove time, add a negative leap second, and speed up global clocks for the first time ever.

Scientists have puzzled over the cause, although experts have suspected a phenomenon known as the “Chandler Wobble” could be having an impact. The Earth’s rotational speed is constantly varying due to the complex motion of its molten core, oceans and atmosphere, and the action of celestial bodies such as the moon.

The friction of the tides and the changing distance between the Earth and the Moon cause diurnal variations in the speed at which the planet rotates on its axis. The Chandler Wobble is the change in the Earth’s rotation about its axis and usually causes the Earth’s rotation to increase, meaning it takes longer to complete a rotation. But in recent years the spin has become less wobbly.

dr Leonid Zotov of the Sternberg Astronomical Institute believes this lack of wobble is behind the faster days.

In recent years, the “Chandler Wobble” has become less wobbly

“The normal amplitude of the Chandler Wobble is about ten to four feet at the surface, but it disappeared from 2017 to 2020,” he told the website Timeanddate.

Other factors that can affect it include snow forming on the mountains of the northern hemisphere and then melting.

Global warming is also expected to have an impact by melting ice and snow at higher elevations, but is thought to be relatively small.

Changes in the length of a standard day were only discovered after highly accurate atomic clocks were developed and compared to fixed stars in the sky in the 1960s.

The final leap second was added on New Year’s Eve 2016 when the clocks stopped for a second to allow the Earth’s rotation to catch up.

The International Earth Rotation Service, based in Paris, monitors the planet’s rotation and notifies countries six months in advance if leap seconds need to be added or removed.

However, the leap second could be eliminated altogether next year when the World Radio Conference decides whether to rely entirely on atomic time.

Britain opposes the move because it would sever ties with solar time forever. (© Telegraph Media Group Ltd 2022)

Telegraph Media Group Limited [2022]

https://www.independent.ie/news/environment/time-is-flying-global-clocks-may-soon-have-to-be-sped-up-to-match-slower-rotation-of-the-earth-41881053.html Time is flying by – global clocks may soon need to be sped up to match the Earth’s slower rotation

Fry Electronics Team

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