What is the inner core of the Earth?
Article Source: Wiley Online Library
Why you should care
The Earth’s inner core is a fascinating mystery lying at the heart of our planet. Composed of solid metal, this region influences the magnetic field that protects life on Earth. Understanding the core helps scientists decode the planet’s evolution, earthquakes, and geodynamics, making it crucial for exploring our world’s past and future.
Answering the question… What is the inner core of the Earth?
The Earth’s inner core is a solid sphere primarily made of iron and nickel, with a radius of approximately 1,220 km (758 miles). It sits at the planet's center, surrounded by a liquid outer core. Temperatures here soar to 5,000–7,000°C (9,000–12,600°F), comparable to the surface of the Sun. Despite its intense heat, immense pressure keeps it solid. The core generates Earth’s magnetic field, vital for shielding the atmosphere from solar radiation.
How was the study done?
The study used seismic wave data from earthquakes to analyze how these waves travel through the Earth’s layers. Scientists employed computational models to simulate core conditions and compared findings with laboratory experiments replicating extreme temperatures and pressures. This multi-method approach helped confirm the composition and solid state of the inner core.
What was discovered?
- The inner core is 99% iron and nickel, with lighter elements like silicon and sulfur making up the rest.
- It rotates slightly faster than the Earth’s surface, completing an extra rotation roughly every 70 years.
- Seismic wave studies revealed its anisotropy: waves travel faster along some directions, hinting at its crystalline structure.
- The core formed about 1 billion years ago, when cooling caused iron to solidify under immense pressure.
- The inner core’s growth adds about 1 mm in radius annually, transferring heat to drive mantle convection and tectonic activity.
Why does it matter?
The inner core is essential for maintaining Earth’s magnetic field, which protects life from harmful solar winds. Its growth and properties provide insights into our planet’s thermal and geological history. By studying the core, we gain a deeper understanding of Earth’s interior dynamics and its impact on surface phenomena like earthquakes and climate.