Planet Earth has recorded its shortest day since scientists began using atomic clocks to measure the speed of its rotation.
Earth’s time systems can prove fairly baffling for
anyone who doesn’t have a PhD in Horology, as we learnt the hard way trying to
figure out why the clocks were going forward as a child – only understanding
that we were being dragged out of bed for school an hour earlier than the week
before.
But the plot thickens further still, as Earth is
actually spinning faster than it used to and recently recorded a time that was
the fastest scientists had ever seen.
On 29 June 2022, Earth completed one spin in 1.59
milliseconds less than its usual 24-hour rotation, in turn setting the record
for the shortest day – and the latest in a series of speed records for our
planet since 2020.
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It's possible that melting of glaciers put less weight
on rock at the poles, which therefore rebound upwards and makes the planet
rounder. The effect of that could make it spin more quickly and could even
slightly change its tilt. |
And it came pretty close again more recently, having
completed the spin in 1.5 milliseconds shorter than 24 hours.
How fast is Earth rotating?
However, in the last few years the atomic clocks have
shown that Earth rotation is now speeding up. In fact, we could be beginning a
50 year period of shorter days.
In 2020 scientists recorded the 28 shortest days since
1960. Last year that trend did not continue, with the shortest day in 2021
being longer than in the previous year.
However, on June 29, 2022 our planet completed its
quickest-ever spin, followed quickly by a day that lasted 1.50 milliseconds
less on July 26, 2022.
The previous record for the shortest rotation was July
19, 2020, when the Earth’s rotation took 1.4602 milliseconds less than 24
hours.
As reported by Time and Date, the current downward
trend in the length of the shortest day could be linked to Earth’s ‘inner or
outer layers, oceans, tides, or even climate’, but scientists remain unsure.
At the forthcoming annual meeting of the Asia Oceania
Geosciences Society, which takes place next week, Leonid Zotov and colleagues
Christian Bizouard and Nikolay Sidorenkov will argue that the decrease may be
related to the ‘Chandler wobble’, the term given to a small and irregular
movement of the geographical poles across the surface of the globe.
Reference: Time and Date
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