Scientists have discovered that the center of the Earth may be more complicated than previously believed.
Researchers have discovered that the Earth’s inner core may contain a secret chamber, consisting of a distinct central region nestled within an outer shell. Previously, scientists believed that the inner core was a solid ball of nickel and iron. However, using a type of seismic wave that travels through and bounces back and forth through the Earth’s core, researchers have confirmed the existence of this innermost inner core. Of the 200 earthquakes with a magnitude of 6 or larger analyzed, 16 produced seismic waves that bounced through the inner core multiple times.
The Earth’s core generates the planet’s magnetic field, which protects the planet’s inhabitants from radiation. The core is approximately 6,600 kilometers across and consists of two main parts: a liquid outer core and a solid inner core. As iron-rich fluid circulates in the outer core, some of the material cools and crystallizes, sinking to form a solid center, generating Earth’s magnetic field.
Different minerals and structures within the Earth’s interior can alter the speed of seismic waves traveling through it, giving scientists clues to its composition. Seismic waves traveling through the innermost part of the Earth move slightly slower in one direction relative to the planet’s poles than in other directions, suggesting there is an oddity in that region, potentially a difference in crystal structure. Scientists suggest this hidden heart may be a long-preserved remnant of the core’s early formation.
Seismologists Hrvoje Tkalčić and Thanh-Son Phạm estimate that this inner heart is about 600 kilometers across, roughly half the diameter of the full inner core. The direction of the slowest waves is about 50 degrees relative to the Earth’s rotation axis, offering further insight into the region. However, the exact source of the wave slowdown is unclear, potentially related to the iron crystals’ structure or a different crystal alignment caused by a long-ago global event that changed how inner core crystals solidified.
While these observations provide valuable contributions, their interpretation of the inner core’s structure from these waves is uncertain. As the waves bounce back and forth, they can weaken, making it challenging to see in the data. More observations will be necessary to reveal what these new data can inform researchers about the heart of the planet.
