Scientists reveal how Earth may have gotten its water

Interactions between early Earth’s magma ocean and a molecular hydrogen atmosphere may have given rise to water

Earth’s water originated from interactions between the hydrogen-rich atmospheres and magma oceans of the planet’s formative years, according to a new study.

Previous research suggested that Earth and the other rocky planets in the Solar System accreted from the disk of dust and gas that surrounded our Sun in its youth.

Studies have theorised that during the Solar System’s early phases, large objects crashed into each other forming the proto-planet that eventually formed Earth.

The planet then grew larger and hotter, melting into a vast magma ocean due to the heat of collisions and radioactive elements, researchers had found.

And over time as the planet cooled, the densest material sank inward, separating Earth into its three distinct layers – the metallic core, the rocky mantle, and the crust, researchers, including those from the University of California Los Angeles in the US, say.

In the latest study, published recently in the journal Nature, scientists developed new models for Earth’s formation to see if the blue planet’s distinct chemical traits could be replicated.

They showed that during Earth’s early existence, interactions between the magma ocean and a molecular hydrogen proto-atmosphere could have given rise to some of the planet’s signature features, such as its abundance of water.

Researchers used mathematical approaches to model the exchange of materials between molecular hydrogen atmospheres and magma oceans by looking at 25 different compounds and 18 different types of reactions.

The complex interactions between various chemicals they simulated yielded data about Earth’s possible formative history.

In the simulated early Earth, interactions between the magma ocean and the atmosphere resulted in the movement of large masses of hydrogen into the metallic core, the oxidation of the mantle, and the production of large quantities of water.

Scientists say these interactions would have generated “copious” amounts of water even if all of the rocky material that collided to form the growing planet was completely dry.

While other water sources such as from comets and meteorites may have also been possible, they say these do not prove necessary to explain Earth’s current state.

“This is just one possible explanation for our planet’s evolution, but one that would establish an important link between Earth’s formation history and the most common exoplanets that have been discovered orbiting distant stars, which are called Super-Earths and sub-Neptunes,” study co-author Anat Shahar from Carnegie Science said.

Researchers part of the study are currently attempting to reveal the chemical makeup of the Milky Way galaxy’s most common planets and to develop a framework for detecting signatures of life on distant worlds.