Earth accelerates its rotation by 2020!

En 2020, la Terre a tourné plus vite. © FrankBoston, Adobe Stock

In 2020, for the first time since measurements began 50 years ago, the Earth is spinning faster than usual. Scientists predict that this will be the case in 2021 as well. Will we use a leap to set the time? Asking the question.

We all wanted to use it to achieve this Year 2020. It seems that even the earth has done everything to achieve it. She began to spin a little faster than usual. Until then, the shortest day record was held on July 5, 2005. Our planet turned itself on at 1.0516 milliseconds, averaging 86,400 seconds a day. Break this record in 2020 … 28 times! On July 19, he set a new record of 1.4602 milliseconds.

No need to worry anyway. There may be several circumstances The speed of the earth. The Movements Of his heart, of the oceans, of his Atmosphere. And more. Moreover, on 27 occasions since 1972, a leap has to be taken to adjust the astronomical time and the given time. Atomic clocks. On December 31, 2016, 23 hours 59 minutes 59 seconds was added to one second.

Remove a jumper?

But at a time when the international community is questioning the merits of the principle, scientists are wondering whether it is necessary to remove a leap for the first time. Because in 2021 they expect The earth rotates at least quickly.

According to their calculations, by 2021, the average day is expected to be 0.07 milliseconds less than the average of 86,400 seconds. July 9 could mark a new record of less than 1.88 milliseconds. Throughout the year, Atomic clocks It can be delayed by about 24 milliseconds. But in principle, the use of a leap occurs Length More than 400 milliseconds per day. So in 2016 we crossed 490 milliseconds.

One more second in 2016: when the earth is slowing down

Everyone knows that, timeSilver. To maintain the timing of atomic clocks and the stability determined by the Earth’s rotation, an additional second, called a jump, will be added on December 31, 2016.

Article Laurent Sacco Published on 12/30/2016

Since 1972, the Central Bureau of the International Service of Earth Rotation and Reference Systems, located at the Paris Observatory, has added one second to the periodically coordinated Universal Time (UTC). Earth’s rotation, used to define universal time (UT) from the Earth’s direction Stars, Not permanent over time. Therefore it is necessary to make adjustments if we wish to comply with the UTC time, based on which it is more consistent. Atomic clocks.

However, its modifications must be kept in mind Rotation Not doing it regularly. Thus, the second of the universal time to be added will not result in a decrease in the speed of rotation of our planet. As a result, this addition may occur for several consecutive years or, conversely, may be postponed indefinitely. One day we may have to cut a moment.

Calculate jump time in seconds …

Anyway, after this system came into existence, we had to add 26 seconds to UTC. These additions are usually scheduled for January 1, or July 1 at midnight. Ae The transition from 2016 to 2017 is scheduled.

An addition The second jump The globalization of exchanges with the Internet and the use of satellites, especially with GPS, are doomed to disappear because they do not fit well with a time based solely on atomic clocks. The disappearance of a UT time in favor of a UTC time can be accompanied by other problems that need to be solved. In the meantime, the training of the jump second is maintained at least until 2023.

One more second in 2005

Article by the Paris Observatory, published on 12/30/2005

On January 1, 2006, at one o’clock in the morning, the watches were delayed for a moment. Very unusually, the minute between 59 minutes and 1 hour at midnight lasts 61 seconds instead of the usual one second or 60 minutes. Any clock that normally counts 60 seconds for that clock will display “1 hour” per second. In advance, it will have to be corrected, at least for the second time closest to the legal time.

On the international “UTC” time scale, this extra second, or “jump”, occurs just before midnight on December 31, 2005. So scientists think it’s from 2005. But in France, the time of day is different due to the time difference compared to the UTCWinter (+1 hours), it will definitely arrive in 1 hour on January 1 … 2006.

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Playing this second at the Paris Observatory. In fact, time-space reference systems – the CRTE department – play an important role in this event through their work in the areas of rotational measurement and time metrology.

The rotation of the earth, which determines the passage of day and night, slows down in the long run, mainly due to the effects of the Looney-solar attraction. In addition, our planet has its internal components (nucleus, Coat) External (atmosphere, oceans).

However, measuring time now is irrational to the moods of the earth, thanks to 250 atomic clocks from many countries around the world, including 25 in France. Together, they make it possible to calculate Coordinated Universal Time – UTC (1).

Because UTC is so regular, a change between the time and time of day and night that determines the rotation of the earth is immediately apparent.

This change is annoying to some ApplicationsAccording to an international agreement signed in 1972, the difference between the two should never exceed one second (2). This is what leap seconds use: When the offset between UTC and the time associated with the Earth’s rotation approaches one second, the inclusion of a leap second in UTC allows these two scales to be reset. Between them.

The Paris Observatory provides scientific services commissioned by national and international organizations. It is for this reason that the International Service for Earth Rotation and Reference Systems – IRS, located at CRTE, is responsible for predicting and announcing these leap moments. This decision is implemented by the responsible international and national authorities Expansion Time.

Prolonged slowdown in Earth’s rotation speed (in red) since 1830.
The pink curve represents the influence of the Earth’s liquid core.

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For France it is LNE-SYRTE (3) Who is responsible for this mission? This other component of SYRTE produces the coordinated universal time of the Paris Observatory – UTC (OP). The French Clock’s talking clock, hosted at the Paris Observatory, uses this high – accuracy reference to broadcast French legal time; You can hear it by dialing 3699. The legal time based on UTC (OP) is transmitted transparently by encoding on the carrier wave of the French Inter, so that it can be used by laboratories at any time, manufacturers, communities, etc. (4).
Several years of international negotiations will lead to a change in this provision. The UTC will then separate from the Earth’s rotation, and we no longer need to add jumps.


(1) The International Bureau of Weights and Measures – BPM, an international organization based in Savres, is responsible for calculating UTC. This is called the “paper” time scale, which can be up to 6 weeks late. Any country in need of efficient time metrology should identify the approximate version of UTC in real time. For France, this reference is the unified Universal Time of the Paris Observatory – UTC (OP).

(2) Until the 1960s, the unit of one second was defined in 1900 as the 86400th part of the average solar day. Today it is defined as 9 192 631 770 radiation period. HyperfinsGround state Of ‘Atom Of Cesium 133.

(3) National Meteorology and Testing Laboratory – LNE creates a laboratory responsible for producing and supplying national references within a framework agreement between the Paris Observatory and CNRS, SYRTE and LNE-SYRTE. Without the metrology of time Frequencies.

(4) A partnership between the French Chamber of Watchmaking and Microtechnics – CFHM and LNE manage the way to propagate legal time.

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