Something inside the Earth is 'stretching' the length of the day

(NLDO) - "Underground forces" are constantly stretching or shrinking the length of a day on Earth in different cycles.

A new study from the Swiss Federal Institute of Technology (ETH Zürich) suggests something hidden in the Earth's core is changing the length of the day.

Scientists have long pointed out that a day is not always exactly 24 hours long, but is continuously stretched and contracted by many "hidden forces" and has 3 cycles.

Something deep inside the Earth, right at the core-mantle boundary, is stretching or contracting the length of the day - Illustration AI: Thu Anh

According to Science Alert, the first fluctuation is an increase/decrease of about 1.72 milliseconds per century, due to a combination of the swelling of the Earth's crust after the thick layer of ice that compressed it since ancient times gradually thinned, combined with the impact from the Moon.

On a decade scale, 2–3 millisecond fluctuations are associated with large-scale flows in the Earth's liquid core.

But there is another fluctuation about 3-4 milliseconds later every day and its cause remains a mystery.

The timing of the upheaval matches up with movement at the core-mantle boundary. So the Swiss team created a model that combines “artificial neural network” technology with paleomagnetic measurements on ancient rocks, as well as modern magnetic field measurements.

They also used available data on Earth's rotation based on eclipse data and lunar occultations — when the Moon obscures a planet or star from Earth's view — dating back to 720 BC.

The results show that the impact of changes in the Earth's ice and water masses is much smaller than previously thought.

Furthermore, the fluctuations on millennial time scales are consistent with simplified models of the magnetohydrodynamics of the Earth's outer core.

In general, this means that there is a "third force" existing in the boundary region between the Earth's core and mantle.

Writing in Geophysical Research Letters , the researchers say they can't yet prove exactly what it is, but the results suggest the importance of the planet's internal geodynamics to the diurnal cycle.

To find a final answer, the existing model of the Earth's core needs to be improved.

Source: https://nld.com.vn/thu-gi-do-trong-long-trai-dat-dang-keo-gian-do-dai-ngay-196241223095511686.htm