Earth's Core Appears To Be Leaking Primordial Helium From the Big Bang

Earth's core appears to be leaking primordial helium from the Big Bang, with around 4.4 pounds escaping from the planet's interior every year.

Helium-3 is a light, stable isotope of helium. It is very rare, with most having been generated in the Big Bang—the prevailing theory about how the universe came into existence, when a very hot and dense single point in space exploded, creating matter and sending it out into the universe at a phenomenal rate.

Helium-3 is one of the earliest elements produced in the universe. It is primarily made in nebulae, which are huge spinning clouds of gas and dust.

earth core
Stock image showing the layers of Earth. Scientists saying helium-3 left over from the Big Bang seems to be leaking from Earth's core. Getty Images

Scientists know helium-3 exists inside Earth as it is found in tiny quantities at the surface. It got there as Earth was forming billions of years ago, with the matter left over from the Big Bang. All the material that was spewed out would eventually come together to form the planets, solar systems and galaxies we see today.

On Earth, how and where helium-3 is escaping from is unclear. Understanding where it is coming from could help scientists better understand the circumstances in which Earth was formed.

In a study published in Geochemistry, Geophysics, Geosystems, Peter Olson and Zachary Sharp, from the University of New Mexico, examined the presence of helium-3 at the surface to understand its location and abundance within Earth. They analyzed how much got there and the way it escapes.

"It's basically an accounting (balance sheet) process," Olsen told Newsweek.

Not long after Earth formed, about 4.5 billion years ago, it was hit by another, Mars-sized primordial planet. This event sent material out into space, leading to the formation of the moon.

Olsen and Sharp modeled helium during two key stages of Earth's history—before and after the primordial planet hit. At this latter point, Earth would have been re-melted, causing it to lose much of its helium-3. Using their model, the scientists were able to estimate Earth has between 10 million and 1 billion metric tonnes of helium-3 deep inside Earth's core.

"Because the mantle lost most of its helium-3 during and after the catastrophic moon-forming event, the mantle and core are out of equilibrium [with regards] to He-3, with more now in the core," Olsen said. "So it leaks back into the mantle, like water leaking from high pressure to low pressure."

"Each year, about 2 kg of the rare gas helium-3 escapes from Earth's interior, mostly along the mid-ocean ridge system," said the study's summary.

Earth is made up of matter it accumulated from the environment in which it formed. Having helium-3 at the core suggests Earth formed inside a solar nebula, rather than at its edges.

"It's a wonder of nature, and a clue for the history of the Earth, that there's still a significant amount of this isotope in the interior of the Earth," Olsen said in a statement.