🌍 There would be a small seed hidden at the center of the Earth

Scientists have discovered that our planet's inner core may contain a small seed at its center: a distinct region called the "innermost inner core."

In geology textbooks, we learn that the Earth consists of four layers: the crust, the mantle, the outer core, and the inner core. The latter, a solid ball of iron and nickel about the size of Pluto, is subject to temperatures exceeding 5,000 °C (9,032 °F). The hypothesis of an additional layer at the heart of the inner core was proposed several decades ago, but the data were too imprecise to confirm it.


It is by using seismic waves from earthquakes that researchers probe this inaccessible structure. These vibrations travel through the Earth at different speeds depending on the materials encountered. By analyzing decades of seismic data with an advanced algorithm, a team from the Australian National University (ANU) examined thousands of models. This approach revealed a change in wave behavior at about 650 km (404 mi) from the Earth's center, signaling a boundary within the inner core.


Independent confirmation came in 2023 thanks to a study published in Nature Communications. Researchers used rare seismic signals that bounce multiple times through the Earth, some crossing the core up to five times. These repeated waves revealed a distinct central region, with similar differences.

These results could explain certain anomalies observed in past experiments and studies. However, scientists acknowledge limitations: the uneven distribution of earthquakes and recording stations reduces confidence in some models. Future studies will help fill these gaps and refine our understanding of events buried at the heart of our planet.