Earth's Core May Be Hiding 45 Oceans of Hydrogen

A Hidden Ocean Beneath Our Feet

Scientists have made a remarkable discovery about what lies at the centre of our planet. A new study, led by Dongyang Huang at Peking University, reveals that Earth's core may harbour a staggering amount of hydrogen, equivalent to between nine and 45 times the volume of all the world's oceans.

The Diamond Anvil Experiment

To reach this conclusion, researchers devised an ingenious laboratory setup. They squeezed tiny samples of iron and hydrous silicate glass between diamond anvils, heating them to approximately 5,100 Kelvin while subjecting them to pressures of 111 gigapascals, conditions that closely replicate those found at Earth's centre. The team then used atom probe tomography, whittling samples into needles with tips just 20 nanometres wide and peeling off atoms one by one using a focused ion beam. This allowed them to directly observe how hydrogen, silicon, and oxygen bond together within iron during planetary formation.

Rewriting the Story of Earth's Water

The findings challenge a long-held theory in planetary science. For decades, the prevailing view has been that Earth received most of its water from impacts by comets and icy bodies after the planet had already formed. However, this new research suggests the opposite: most of Earth's water has been with the planet since its formation roughly 4.5 billion years ago, locked away deep in the core during the earliest stages of accretion.

Hydrogen is estimated to represent between 0.07 and 0.36 percent of Earth's core by weight, making the core potentially the largest reservoir of hydrogen on the planet.

Implications for Habitability

The study also sheds light on how Earth developed its protective magnetic field. According to the researchers, the crystallisation of hydrogen, silicon, and oxygen inside the cooling core would have created convection currents, providing a driving force for an ancient geodynamo. This magnetic field is considered indispensable for making Earth habitable, shielding the atmosphere from solar wind and protecting the surface from high-energy charged particles.

Perhaps most intriguingly, if this process proves common among rocky planets, worlds that appear dry from the outside may harbour hidden water deep beneath their surfaces, expanding the search for potentially habitable worlds beyond our solar system.