Did Earth wobble cause shortest day ever recorded?
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Earth has recorded its shortest day since records began in the 1960s.
We get day and night from Earth rotating over 24 hours.
On the 29 June 2022, the National Physical Laboratory in England recorded the shortest day in history at 1.59 milliseconds less than 24 hours.
Meaning the Earth rotated on its axis in less than 24 hours.
But this isn't the first time that this has happened.
In 2020 a company called timeanddate, used data from International Earth Rotation and Reference Systems Service (IERS) to report that Earth had achieved its 28 shortest days since accurate daily measurements using atomic clocks began in the 1960s.
Then, on 26 July this year, the June record was almost beaten again with a day that was 1.50 milliseconds less than 24 hours.
Why is this happening?
Scientists don't know exactly why this is happening but there are some possible explanations.
The Earth's axis is tilted but there is a slight wobble, a bit like you might see with a spinning top.
Things can affect this wobble including the Moon which stabilises the Earth and Ocean tides,
Astronomers Leonid Zotov, Christian Bizouard, and Nikolay Sidorenkov believe it is such a wobble which is causing the rotation to speed up.
Specifically an irregular wobble on Earth's poles called the Chandler Wobble which was discovered in 1891.
Dr Zotov told timeanddate, "from 2017 to 2020 it disappeared."
What happens now if shorter days continue?
The Big Question: Why does the earth spin? We ask Professor Brian Cox
The atomic clock is a clock which measures time by monitoring the frequency of radiation of atoms.
They are used by navigation by satellite systems like GPS.
Universal time is determined by atomic clocks.
On average the trend has been longer days with the Earth's spin slowing down.
To keep time in line with the Earth's rotation, the International Telecommunication Union, a United Nations body, has added occasional leap seconds in June or December so it can catch up.
This last happened in 2016.
But if the rotation continues to go faster some experts have wondered whether a second might be dropped instead of added.
- Published31 July 2019
- Published3 September 2020