EARTH’S INNER CORE (Syllabus: GS Paper 1 – Geography)

Context: Recent studies by scientists indicate that the Earth's core has slowed down significantly, potentially reversing its direction of movement.

Earth’s Inner Core

• About: The innermost part of Earth, located approximately 5,150 kilometers beneath the surface.
• Composition: Primarily of iron and nickel, forming a solid metallic ball.
• Mass: Makes up around 20 percent of Earth’s total mass.
• Size: Has a radius of about 759 miles (1,221 kilometers).
• Temperature and Heat Sources: Extremely hot, with temperatures ranging from 7200–9000℉ (4000–5000℃).
• Heat generated by radioactive decay, residual heat from planetary formation, and heat from outer core solidification.
• Pressure: Under intense pressure of about 3.6 million atmospheres, which maintains its solid state despite high temperatures.
• Surrounding Layers: Outer core, a superhot layer of molten metals, and further by the mantle and crust.

o The boundary with the outer core is known as the Lehman Seismic Discontinuity.

• Magnetic Field: Generates its own magnetic field.

o Contains about 10% of the Earth's total magnetic field energy despite its small volume.

Rotation speed of Earth's core slowing down

• Discovery of Earth's Inner Core: Danish seismologist Inge Lehmann discovered the planet's inner core in 1936, sparking ongoing scientific inquiry into its properties.
• Challenges: Direct observation and sampling of Earth's deep interior are impossible, leading scientists to rely on indirect methods for understanding core dynamics.
• Seismographic Evidence: Data from seismograms, measuring waves from earthquakes and explosions, provide crucial insights into the Earth's core rotation.
• Recent Findings: A study published in June found that the solid inner core's rotation speed has been consistently decreasing relative to the Earth's surface.