Using an instrument that uses the propagation of laser beams, researchers have for the first time measured the Earth’s rotation speed and its fluctuations with an accuracy of 9 decimal places. An important result for many scientific fields.

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(on video) Why don’t we feel that the Earth is rotating? The Earth completes one rotation on its axis in 24 hours, which is…

Everyone knows that the Earth’s rotation is 24 hours, and our planet takes 365 days to revolve around the Sun. Even if these values ​​are more than enough to organize our daily routine, many scientific fields require more precision. Especially because neither the length of the day nor the period of revolution around the Sun is constant. Quantifying these small changes is especially essential for researchers who set up climate models, but also for astronomers.

The rotation speed of the Earth is affected by the presence of a liquid cover.

The Earth is actually not a completely solid body. It has several layers, one of which is liquid: this is the outer core. Perhaps you have already tried the test of hard-boiled eggs and raw eggs? By rotating two eggs we learn that the presence of liquid affects the rotation of the raw egg. At a much higher level of complexity, the same is true for Earth. The presence of a fluid cover, which is not necessarily homogeneous or regular, affects its rotation speed, but also the stability of its axis. Mass movements induced by the movement of this fluid mass speed up or slow down the planet’s rotation. However, these fluctuations, which we have known for a long time, have been determined with extreme precision thanks to a new instrument developed by the Wetzel Geodetic Observatory.Technical University of Munich, It is a ring-shaped laser system whose algorithm has been perfected to allow greater measurement accuracy.

Rotation speed of the Earth with an accuracy of 9 decimal places

Within a sealed enclosure equipped with mirrors, two laser beams are generated, one propagating clockwise and the other counter-clockwise. If the Earth were stationary, both rays would travel the same distance before meeting. But the Earth’s motion in space will induce a small movement of the mirrors: one of the laser beams will have to travel a greater distance than the other. This difference can be measured with great accuracy. This depends specifically on the speed at which the Earth rotates. For the first time, researchers were able to measure these variations in rotation speed with an accuracy of 9 decimal places! The results were published in the journal nature photonics,

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