Earth’s inner core is softer, a study reveals


  • Contrary to the fact the Earth’s inner core is solid, researchers from Australian National University (ANU) have found that it is comparatively softer.
  • In a groundbreaking discovery, Associate Professor Hrvoje Tkalcic and PhD Scholar Thanh-Son Pham are confident that the earth’s inner core is solid.

Facts about the inner core of the Earth:

Radius: 1,220 kilometres (760 miles) i.e. 70 per cent of the Moon’s radius

Composed of: Nickel-iron alloy

Temperature: 5,700 K (5,430 °C) or 9806 °F, which is almost the temperature of Sun

What is inner core made of?

The inner core is made up of two layers outer and inner.

Outer core is 1,355 miles (2,180 km) thick.

Why is the radius of inner core unknown?

  • There is no estimated radius of the inner core; however, it plays a distinct role in making Earth’s magnetic field.
  • The inner core is measured by shear waves, a seismology term, which is so tiny and feeble that it can’t be observed directly.
  • In fact, detecting them has been considered the ‘Holy Grail’ of global seismology since scientists first predicted the inner core was solid in the 1930s and 40s.

Purpose of the Earth’s inner core:

  • According to, when charged particles from the solar wind collide with air molecules above Earth’s magnetic poles, it causes the air molecules to glow, causing the auroras – the northern and southern lights.

How has it been discovered?

  • They came up with a way to detect shear waves, or ‘J waves’ in the inner core – a type of wave which can only travel through solid objects.
  • “It turns out – if our results are correct – the inner core shares some similar elastic properties with gold and platinum. The inner core is like a time capsule, if we understand it, we’ll understand how the planet was formed, and how it evolves,” he added.
  • According to the research published by the university, the wavefield method looks at the similarities between the signals at two receivers after a major earthquake, rather than the direct wave arrivals.
  • A similar technique has been used by the same team to measure the thickness of the ice in Antarctica.
  • The study shows these results can then be used to demonstrate the existence of J waves and infer the shear wave speed in the inner core.

Source: India Today

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