The earth turns faster and faster and scientists do not know exactly why

It is an imperceptible but very real event: on August 5, the land will perform its daily rotation with an advance of around 1.51 milliseconds over the usual 24 hours. Meanwhile, This day will be the shortest of the year.

Because you may not have known it. Therefore, but the duration of a day (the time put by the earth to make very exactly a turn on itself) is not constant in time. Similarly, “An ideal day is supposed to last exactly 86,400 seconds or 24 hours. Furthermore, But since the invention of atomic clocks earth turns faster faster scientists in the 1950s. Furthermore, we know that this duration varies, in a tiny but measurable way, according to a large number of parameters ”, explains Christian Bizouard, French astronomer and research director at the Paris Observatory.

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From that time, scientists understood that the moon played a fundamental role. Nevertheless, The gravitational forces exerted between the earth and the moon exert a braking effect on earthly rotation. It is a slow, but constant process: the earth loses approximately 2 milliseconds per century because of this mechanism.

The traces left by the tide cycles in certain old sedimentary rocks testify that around 2 billion years. ago a land day lasted 20 hours. In the long term, this gradual slowdown is the dominant effect. Since the adoption of international atomic time in 1967. defined independently of astronomical time, it is thus necessary to compensate for the gradual gap which earth turns faster faster scientists is widening between the two by the regular addition of second intercalaire in order to avoid an inexorable drift.

“Negative” interlayer – Earth turns faster faster scientists

But the earth also undergoes seasonal variations in its rotation speed. “” Many factors such as the position of the moon compared to the equator. the melting of ice, earthquakes or the internal movements of the fluid nucleus of our planet, still very poorly understood by scientists, are at the origin of this phenomenon “, explains the French astronomer.

It is for example the distance from the moon from the terrestrial equator which partly explains the current records. The mechanics are comparable to that of a skater who turns on himself, explains Christian Bizouard. When the Moon is getting closer to the poles. this indeed changes the distribution of the masses on the surface of our planet, which leads to a momentary acceleration of rotation earth turns faster faster scientists “As if the earth brought back its arms” near his body.

Associated with oceanic, climatic and atmospheric factors, this phenomenon is at the origin of certain shortest days ever recorded. On July 12, 2024, the blue planet had broken a record by turning with 1.66 milliseconds in advance. In 2025. July 9, July 22 and August 5 will be for this reason the three shortest days of the year with a peak on August 5.

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A mysterious acceleration

What is more misunderstood is that the average trend has been accentuated since 2020. The peaks are increasingly marked, as if the earth was turning faster and faster. This reversal of trend, unprecedented on a contemporary scale, is not very clearly understood. “Oceanic and atmospheric models are no longer enough to explain the acceleration observed since 2020”, underlines Christian Bizouard.

The current situation even leads earth turns faster faster scientists scientists to consider for the first time the introduction of a “Negative second interlayer” In 2029 to compensate for this advance. according to the international service of the rotation of the earth and the reference systems.

In daily life, this difference is imperceptible. But in very specific areas, such as GPS systems, computer networks or telecommunications, this operation is important.

If this acceleration is an anomaly, the phenomenon should not last over time. At geological time ladders, the duration of the day will necessarily end up resuming its natural movement and lengthen. In 200 million years, astronomers estimate that a day will last 25 hours.