Helium Dating to Big Bang Found Leaking From Earth's Core Offers Fresh Clues to Planet's Formation

Findings of the new research are seen as offering additional evidence to support the theory that planet Earth formed inside a solar nebula – a cloud of gas and dust -about 4.6 billion years ago.

Helium-3, a rare isotope of helium gas dating back to the time of the Big Bang, is leaking out of Earth’s core, a new study has shown.

Furthermore, this discovery, outlined in a paper published in the American Geophysical Union (AGU) journal Geochemistry, Geophysics, Geosystems, feeds into the theory that Earth was formed inside the molecular cloud called a solar nebula.

Helium on Earth comes in two stable isotopes: the most common one, helium-4, accounts for about 99.99986 percent of all the helium on our planet. It is primarily the product of the radioactive decay of uranium and thorium, made on Earth. The other stable isotope - Helium-3 (3He) - is mostly primordial, accounting for just about 0.000137 percent of Earth's helium.

About 2,000 grams of helium-3 leak out of the Earth annually, “about enough to fill a balloon the size of your desk,” according to lead study author Peter Olson, a geophysicist at the University of New Mexico.

According to the scientists, most of the Helium-3 formed during the Big Bang in the Universe, roughly 13.8 billion years ago.

“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… The solar nebula only lasted a short time — just a few million years. Helium-3 and other nebula gasses were incorporated into the Earth when it formed. This implies that Earth and terrestrial planets were in the process of forming very early in solar system history,” Peter Olson was cited by Forbes as saying.

Interestingly, before this research, geoscientists tended to consider Earth’s inner core as a closed system. However, according to Olson, the team of researchers used new models in their analysis, based on mass spectrometer measurements of helium-3 from volcanic basalts discovered in Iceland and Hawaii.

The Helium-3 isotope was detected leaking out of Earth's interior mostly along the mid-ocean volcanic ridge system. The only way significant amounts of helium-3 could remain within the planetary core is if it were formed in a thriving nebula, claim the researchers.

This infrared image from NASA's Spitzer Space telescope shows a cloud of gas and dust carved out by a massive star. A drawing overlaid on the image reveals why researchers nicknamed this region the "Jack-o'-lantern Nebula."

© NASA . JPL-Caltech

Olson, together with geochemist Zachary Sharp of the University of New Mexico, modeled Earth's processes involving helium as the planet evolved, starting with the process during which the protoplanet accumulated and incorporated helium. Then, they modelled helium “inventory” after the so-called Great Impact, when an object one-third the size of the Earth is believed to have hit our young planet, re-melting the mantle. During that event, they believe that most helium locked inside the mantle would have been lost. However, as the core is more resistant to impact, it could serve as a reservoir for surviving helium-3.

Other primordial gases may be leaking from Earth's core, which has been in a liquid state over much of our planet’s history, says the study. This information could offer even more revelations about the composition of the solar nebula.

“Future work looking for other nebula-created gases, such as hydrogen, leaking in similar rates and locations as 3He could be a smoking gun for the core as the source... There are many more mysteries than certainties,” summed up Dr. Olson.