New research indicates Earth’s core may contain as much hydrogen as 45 oceans worth of water, suggesting our planet’s water originated during its formation, not from later impacts. This discovery fundamentally shifts our understanding of Earth’s early history and the origins of its life-sustaining environment.
How Scientists Unlocked the Core’s Secrets
For decades, scientists have debated whether Earth’s water came from asteroids or comets. The core, primarily iron, is not dense enough to be solely iron – meaning lighter elements must be present. Measuring these elements directly is impossible, so researchers rely on extreme simulations: squeezing materials between diamond anvils at thousands of degrees Celsius and immense pressure to mimic core conditions.
Hydrogen, being light, is hard to measure in these experiments; it diffuses easily. The new study, led by Dongyang Huang at Peking University, overcame this challenge by precisely isolating hydrogen within iron and hydrous silicate glass. By bombarding the samples with an ion beam to analyze individual atoms, the team determined that hydrogen makes up 0.07–0.36% of the core’s weight.
What This Means for Earth’s Origins
This level of hydrogen suggests Earth formed in a gas-rich disk where hydrogen was abundant. If true, water wasn’t delivered later but was present from the start. “It really changes the way we think of where our water comes from,” says Hilke Schlichting, a planetary scientist not involved in the study.
The presence of hydrogen also explains the planet’s magnetic field. As the core cooled and crystallized, convection currents would have been driven, powering a geodynamo that protects Earth from harmful solar radiation. This magnetic field is crucial for maintaining a habitable environment.
The Implications of Hydrogen in the Core
The existence of this much hydrogen in the core proves that water was present from the beginning, rather than being delivered by late heavy bombardment. This supports the idea that Earth was always a water-rich planet. The team’s work also shows that the Earth’s magnetic field, essential for life, is powered by convection currents driven by these early elements.
The new study confirms that Earth’s water cycle has been in operation for at least 4.5 billion years, since the core began solidifying. This research clarifies how Earth evolved into the habitable world we know today.
