A recent study proposes that Earth’s core experiences a periodic wobbling every 8.5 years.

In a recent discovery in China, scientists revealed a phenomenon at the Earth’s core: a periodic wobbling occurring approximately every 8.5 years. The researchers propose that this oscillation results from a minute misalignment between the inner core and the Earth’s mantle—the layer beneath the planet’s crust—according to their newly conducted study. Situated roughly 1,800 miles (2,896 km) beneath the Earth’s surface, the core comprises a fluid outer boundary and a predominantly solid inner layer.

This zone plays a crucial role in various geophysical dynamics of our planet, influencing factors such as the length of each day and the Earth’s protective magnetic field, which shields against harmful solar radiation. The identified tilt in the inner core has the potential to instigate alterations in the shape and movement of the liquid core, thereby introducing a prospective shift in Earth’s magnetic field, as outlined in the study published on December 8 in the journal Nature Communications.

In an effort to gain a deeper understanding of the Earth’s core dynamics, geophysical researchers, led by Hao Ding from Wuhan University, conducted an analysis in 2019 focusing on the Earth’s polar rotation—the movement of its rotational axis relative to the crust. This examination revealed a subtle deviation in polar motion occurring approximately every 8.5 years, hinting at the possible existence of an “inner core wobble,” analogous to the spinning top’s characteristic oscillation. In their recent study,

Ding and his co-authors validated this periodic cycle by assessing minor fluctuations in global day length, which is influenced by the periodic movement of the Earth’s rotational axis. They compared these variations with the previously identified shifts in polar motion, supporting the notion of an “inner core wobble.” Their data indicates that this wobble is likely induced by a 0.17-degree tilt between the Earth’s inner core and mantle. This finding challenges the conventional Earth rotation theory, which assumes the alignment of the rotation axes of the Earth’s inner core and mantle, as explained by Ding in an email to Live Science.

This tilt suggests a potential higher density in the northwestern hemisphere of the inner core compared to the rest of this layer, along with a discernible density difference between the Earth’s inner and outer core, as indicated by the research. According to John Vidale, a professor of Earth science at the University of California, the new study contributes to the understanding of the composition disparity between the metal in the solid inner core and the liquid outer core.

Additionally, it provides estimates of the direction and speed of the inner core’s wobble. While not offering immediate benefits for humanity, Vidale notes that the research adds fundamental knowledge essential for comprehending our planet. The research team, as part of their analysis, eliminated potential influences from the atmosphere, oceans, and hydrology that could have contributed to the polar motion deviation, aside from the inner core wobble.

However, Vidale acknowledges the complexity of confirming the absence of these influences, stating that assembling such analyses requires expertise from various fields. Looking ahead, this discovery holds the potential to enhance our understanding of the interplay between Earth’s inner core and processes that impact humanity, ranging from seismic activities to changes in the magnetic field.

This article is republished from live science under a Creative Commons license. Read the original article.