A groundbreaking study suggests that helium-3, a rare isotope formed during the early solar system, may be trapped within Earth’s core. The discovery could reshape our understanding of planetary formation, indicating that Earth might have formed much faster than previously estimated.

Helium-3, unlike its common counterpart helium-4, originates from the primordial gas cloud that created the solar system. While traces of helium-3 have been found in volcanic hotspots and ocean ridges, scientists have long debated how the isotope remained trapped for billions of years, given its highly volatile nature.

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Helium and Iron Interaction at Core Conditions

Researchers at the University of Tokyo, led by Kei Hirose, conducted high-pressure experiments to determine whether helium could mix with iron under extreme conditions similar to Earth’s core.

Using a diamond anvil, they compressed iron and helium to pressures ranging from 50,000 to 550,000 times Earth’s atmospheric pressure. The samples were heated to temperatures between 727 and 2,727 degrees Celsius before being depressurized and analyzed at cryogenic temperatures to prevent helium escape.

The study, published in Physical Review Letters, found that solid iron could incorporate up to 3.3% helium, suggesting that helium-3 might remain trapped in the core for extended periods.

What It Means for Earth’s Formation

Geophysicist Peter Olson from the University of New Mexico stated that the findings confirm helium’s compatibility with Earth’s solid core. However, he noted that only about 4% of the core is solid, with the rest being in a liquid state. Further research is needed to determine if helium-3 could also be retained in the liquid core.

The study also suggests that if helium-3 is indeed present in Earth’s core, it supports the theory that our planet formed rapidly—within a few million years. A slower formation process, spanning nearly 100 million years, would have likely resulted in minimal helium retention.

This discovery provides crucial insights into the timeline of Earth’s formation and adds to the growing body of research on the planet’s deep interior.