Scientists from Switzerland believe that changes in the Earth's molten iron core may be responsible for small fluctuations in the length of a day on the planet. Although the length of a day appears stable, it actually varies, and this pattern has become noticeable over long timescales. The study was published in the journal Geophysical Research Letters (GRL).

The Earth rotates around its axis, but its motion does not always align perfectly with 24 hours. The length of a day is influenced by many factors, including the gravitational effect of the Moon and processes in the Earth's crust. Changes in mass distribution, such as melting ice or changes in water volume, can also affect the planet's rotational speed. However, over timescales of several thousand years, scientists have noticed minor fluctuations in the length of a day that are difficult to explain by known factors. One possible explanation is movement at the boundary between the Earth's core and mantle, which could lead to such changes.

The researchers developed a new approach for more accurate analysis of these fluctuations. They used neural networks, along with data on Earth's magnetic field obtained from rock analyses. Data on solar eclipses were also used to track changes in the planet's rotation over millennia.

The results showed that the impact of changes in ice and water mass on the length of a day is much smaller than previously thought. Instead, the fluctuations correspond to models that explain the movement of the Earth's liquid outer core.

However, the scientists emphasize that the issue remains unresolved, as modeling such small changes requires further improvements and more accurate data. Future work will focus on creating more complete models to better understand how various processes in the Earth's interior affect the length of a day.