Tick-tock, tick-tock… The time that passes on our screens gives us the illusion of unshakeable straightness and perfection.
The celestial mechanics on which it is based, however, are more confusing: 2024, a leap year, reminds us that the Earth does not really take 365 days to revolve around the Sun, but 365.2425.
These decimals require you to mark February 29 in your diaries every four years or so so as not to find yourself, after a while, celebrating Christmas in Paris in the middle of summer.
As if this calendar quirk were not enough, it is established that the length of the day varies.
For nine years, the Earth has also tended to rotate a little more quickly, shortening our days.
June 29, 2022 was thus the shortest ever recorded: 24 hours minus 1.59 milliseconds.
How to explain this imperceptible acceleration?
The change, which is quite unpredictable, is thought to be the result of interactions between the Earth's fluid core and its mantle.
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