The Earth’s Core Is Solid, According To New Research

A cutaway showing planet Earth's layers
Johan Swanepoel / Shutterstock

A new study by a team of researchers in Australia is turning everything we know about the Earth’s core upside down. According to R&D, scientists from the Australian National University have found a way to confirm that the planet’s core is, in fact, solid, something scientists have hypothesized, but have never proven.

Researchers used seismographs to measure waves moving through the Earth after an earthquake takes place. By analyzing the data from these seismic waves, scientists determined that the inner core of the planet is solid. Hrvoje Tkalcic, who co-authored the study, says that the data indicates that the core is similar in elasticity to gold and platinum.

“We found the inner core is indeed solid, but we also found that it’s softer than previously thought. 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 said.

ANU researchers looked at the “J-phase” of seismic waves as they pass through the Earth’s core. These waves surge up and down like ocean surf. As the waves pass through the Earth’s core, it gives researchers information on the center of the planet’s elasticity. Previously, J-phase waves have been too quiet for scientists to analyze, but the ANU scientists figured out how to “hear” the waves and understand what they indicate.

According to Tkalčić, the study utilized a global network of stations to measure and compare every single large earthquake on the planet. The resulting data confirms what scientists have suspected, but haven’t been able to prove with any certainty. It’s like looking at a “fingerprint of the earth,” said Tkalcic.

Tkalcic admits that there is still plenty we don’t know about the planet’s core. Given the fact that researchers only been able to dig about 7.5-miles into the crust, and the core lies about 3,958 miles deep, that we have any knowledge of the planet’s center is exciting. This latest study gives scientists an amount of insight that they’ve never had access to before.

“For instance we don’t know yet what the exact temperature of the inner core is, what the age of the inner core is, or how quickly it solidifies, but with these new advances in global seismology, we are slowly getting there,” Tkalcic said.

A similar technique was recently used to measure the thickness of the ice shelves in Antartica.