Scientists have found out that Earth’s core is growing lopsided; however, they don’t the reason behind it yet. The solid-iron core at the middle of Earth has been growing faster beneath Indonesia’s Banda Sea, according to seismologists at the University of California in Berkeley.
The growth on one side of the molten metal is due to iron crystals that form as the molten iron cools. However, something under the planet’s outer core under Indonesia is dissipating heat at a higher rate than the opposite end, which is under Brazil. Due to faster cooling, iron crystallization happens faster, and the growth increases.
Protecting Earth from solar particles
This disparity results in significant implications for the Earth’s magnetic field and the convection currents in the core that generate the field. This is what protects the planet from harmful solar particles.
While the core is solid iron, it has a fluid outer core surrounding it alongside a mantle of hot rock. In the mantle and the outer core, heat moves upwards towards the surface, forcing colder material to go down.
“We provide rather loose bounds on the age of the inner core — between half a billion and 1.5 billion years — that can be of help in the debate about how the magnetic field was generated prior to the existence of the solid inner core,” said Barbara Romanowicz, emeritus director of the Berkeley Seismological Laboratory (BSL).
“We know the magnetic field already existed three billion years ago, so other processes must have driven convection in the outer core at that time.”
Tectonic plates could be the reason
The younger inner core hints that in the Earth’s history, the heat that keeps iron in liquid form did not come from the crystallization of iron, but from light elements separating from iron.
However, it still doesn’t answer a complicated question: “If the inner core has only been able to exist for 1.5 billion years … then where did the older magnetic field come from?” assistant BSL scientist Daniel Frost posed. “That is where this idea of dissolved light elements that then freeze out came from.”
Tectonic plates could be one explanation, when they sink into subzones, they cool the mantle with cold plates. However, it’s not known for certain that mantle cooling has an impact on the inner core.
