Space & Science

Earth records its shortest day ever with 1.59 milliseconds less than the 24-hour rotation

It was over so quickly! Earth records its shortest day ever with 1.59 milliseconds less than the 24-hour rotation

Planet Earth has recorded its shortest day since records began.

The 1.59 milliseconds snipped from the usual 24-hour rotation on June 29 raises the prospect of a leap second having to occur to keep the clocks aligned. It would be the first time that world clocks would be sped up.

Earth’s rotation has been known to slow down, with 27 leap seconds needed to maintain accurate atomic time since the 1970s. The last was on New Year’s Eve 2016, when clocks stopped for a second to allow the Earth to catch up.

Other factors can impact the length of days on Earth, including the accumulation of snow on the mountains of the northern hemisphere in winter, and then its melting in summer.

But since 2020, this phenomenon has reversed – the previous fastest day was -1.47 milliseconds on July 19 of that year. Humans cannot detect the change, but it could affect satellites and navigation systems.

Experts say the “Chandler Wobble” – a change in the Earth’s rotation on its axis – could be to blame. Dr Leonid Zotov, of the Sternberg Astronomical Institute in Moscow, said: “Normal oscillation amplitude is about four meters on the Earth’s surface, but from 2017 to 2020 it disappeared.”

Experts say the ¿Chandler Wobble¿ ¿ a change in the Earth's rotation on its axis ¿ may be to blame

Experts say the ‘Chandler Wobble’ – a change in the Earth’s rotation on its axis – could be to blame

Other factors can influence the length of Earth days, including the accumulation of snow on the mountains of the northern hemisphere in winter, and then its melting in summer.

Global warming is also considered to have an effect by melting ice and snow at a faster rate.

The International Earth Rotation Service in Paris monitors the rotation of the planet and will advise countries when leap seconds should be added or removed, giving them six months notice.

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