For years, scientists have tried to understand what’s hidden in the Earth. Now, a recent investigation has revealed something surprising: the Earth’s core could contain a great amount of hydrogen, higher than the one existing in every ocean of the surface.
Even though the oceans cover 70% of our planet and they seem so large, this new study suggests the truly great deposit of hydrogen could be in the deepest part of the Earth. So, let’s find out more about this discovery.
How much hydrogen is there in the Earth’s core?
According to the study published in Nature Communications, the Earth’s core could contain between 9 and up to 45 times more the amount of hydrogen there is in all oceans together!
Scientists explain that hydrogen could represent between 0.36% and 0.7% of the total weight of the Earth’s core. Although this percentage seems small, it’s actually very large if we consider the core’s weight and size.
Dongyang Huang, the lead author of the study and an assistant professor at the School of Earth and Space Sciences at Peking University, explained that this finding suggests most of the Earth’s water — which is the main source of hydrogen on the planet — was acquired during the planet’s formation. This challenges the idea that water mainly arrived later through comet impacts.
Huang stated that the core would have kept most of the water in the first million of years of the Earth’s history. After the core, the mantle and the crust contain the next largest amounts of water. So, the surface, where life exists, contains the least.
How Earth was formed
More than 4.6 billion years ago, rocks, gases, and dust around the Sun collided and gradually formed a young planet: the Earth. With the passage of time, these collisions lead to three main layers: core, mantle, and crust.
Deep inside our planet, under great pressure, a dense, hot, metallic core formed. It is made mainly of iron and nickel. This core is responsible for generating the Earth’s magnetic field, which protects the planet.
Rajdeep Dasgupta, a professor of Earth system science at Rice University in Texas, explained that hydrogen could only enter the metallic liquid that formed the core if it was available during the main stages of the Earth’s growth.
Why is it so difficult to study the core?
The Earth’s core is too deep to study it directly. What’s more, the conditions there are extreme, with pressures, and very high temperatures that are difficult to reproduce in the lab. Also, hydrogen is the lightest and smallest element, which makes it so hard to measure it.
In the past, scientists tried to estimate the amount of hydrogen by observing how iron’s crystal structure changed using X-ray diffraction. However, results varied greatly — from very small amounts to estimates equal to more than 120 “oceans” of hydrogen.
Atomic-scale observations
In this new study, researchers used a different method. They sharpened iron samples into extremely small needle-like shapes about 20 nanometers wide. Then they applied a carefully controlled high voltage, which allowed them to ionize and count atoms one by one.
To recreate the conditions of the Earth’s core, scientists melted iron using lasers inside a high-pressure device called a diamond anvil cell. They then used atomic probe tomography to capture 3D images and measure chemical composition at the atomic level.
They discovered that the ratio of hydrogen to silicon was approximately 1 to 1. By combining these results with previous estimates of silicon in the core, they were able to calculate the approximate amount of hydrogen present.
Uncertainties and scientific debate
Despite these results, scientists caution that uncertainties remain. This method is indirect and it doesn’t take into account every possible chemical interaction. For example, Kei Hirose, professor at the University of Tokio, pointed out that hydrogen could even represent between 0.2% and 0.6% the core’s weight, a higher amount than estimated in the new study.
There’s also the possibility that part of hydrogen from the samples had been lost during experiments, which could alter results.
To sum up
This discovery is important for understanding the formation of Earth and the origin of its water. If hydrogen was present during the planet’s early growth, it suggests that water did not arrive only from comets or asteroids after Earth had already formed.
Although further research is needed to confirm the exact amounts, this study opens new possibilities for understanding how our planet formed and how it became a place where life could exist.