Geologists have been studying the inner core of the Earth to gain a better understanding of the magnetic field that protects life on our planet. As the inner core cools and solidifies, it grows by about a millimeter each year. Recent research has revealed that one side of the inner core appears to be growing faster than the other, but the reason behind this asymmetry remains unknown.

The process of crystallization in the inner core began between 1.5 billion and 500 million years ago and continues to this day. As molten iron in the outer core loses heat, it solidifies and forms a new layer in the inner core. The region where this growth is most active is located approximately 1,800 miles (2,896 kilometers) beneath Indonesia’s Banda Sea, where about 60 percent more iron crystals form compared to the other side of the world.

Despite the uneven growth over billions of years, the inner core maintains its spherical shape due to gravity. The growth of the inner core, although a fascinating puzzle, may play a role in generating the Earth’s magnetic field, which is essential for our survival.

The cooling of the inner core is significant for the Earth’s overall functioning. As it cools, it releases heat, causing movement in the outer core. This movement, known as the geodynamo, involves the spinning of liquid iron and generates the magnetic field that shields the Earth from harmful solar winds.

The interactions between different layers of the Earth also play a crucial role. Each layer, from the outer core to the mantle and the crust, affects the layer below it. The inner core transfers its heat, derived from the planet’s formation and the decay of radioactive elements, to each subsequent layer. This heat transfer process could contribute to the varying rates at which the inner core cools. For example, regions with major subduction zones, like Indonesia, experience cooling due to the influx of cooler tectonic plates into the hot mantle, facilitating solidification in the inner core.

While the exact cause of the asymmetry in the inner core’s growth remains unknown, it may explain why the iron crystals within it align along the North-South axis of the Earth’s rotation. This alignment creates an orderly lattice structure that acts as a highway for fast-moving tremors. Seismologists have observed that earthquakes propagate faster between the North and South Poles than across the equator, indicating this alignment of iron crystals.

Further research is necessary to uncover the relationship between this asymmetry and the Earth’s magnetic field. Scientists have long been aware of periodic reversals in the magnetic field’s direction, during which it temporarily weakens. However, the underlying reasons for these phenomena are still not fully understood. Understanding the inner workings of the Earth’s core is crucial due to the vital role it plays in supporting life on our planet.