“New Research Suggests Earth Produced Its Own Water Supply”

SPACE — So far, scientists believe that the origin of earth’s water was brought by ice comets or asteroids when our dry world was just born billions of years ago. Contrary to this popular theory, recent research suggests that planet Earth has produced its own water supply.

This water likely originated from chemical interactions between the hydrogen-rich atmosphere and the magma ocean. According to the researchers, a hydrogen-rich atmosphere envelops the young Earth, while an ocean of magma barely covers the planet’s surface.

“Under these conditions, water forms as a natural by-product of all the chemistry that occurs,” said study co-author Anat Shahar who is a scientist at the Carnegie Institution for Science, Washington DC. The new research was published in the journal Nature on Wednesday, April 12, 2023.

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Earth is the most unique planet in the solar system. Partly because of the large amount of water that dominates the surface of the planet, more than 70 percent. This number is much more than any other planet in our cosmic circle. When and where did so much water come from, however, remains a continuing mystery. Scientists have yet to find a direct and conclusive answer to this.

One popular theory holds that the asteroid impact likely produced most of the planet’s water. However, some research suggests the water locked inside the asteroid is chemically different from water on Earth. And now, scientists say the water supplies that made Earth an oceanic world came about thanks to a hydrogen-rich atmosphere early in the planet’s history.

According to the latest research, water growing within the planet would have occurred if the newborn proto-Earth was 0.2 to 0.3 times its current size. This size is slightly larger than previously thought. To note, the Earth continues to grow by gathering more and more abundant gas and dust around it.

In that case, the young Earth would have been massive enough to survive in its atmosphere for a long time, making it much richer in hydrogen than it is today. Earth’s atmosphere is currently composed of 78 percent nitrogen.

“Simply by changing the initial conditions when the Earth formed, we are able to produce a lot of water that enters the planet and its atmosphere,” Shahar told Space.com.

Incidentally, such hydrogen-rich atmospheres are seen around many recently formed rocky planets outside our solar system. The most common type of exoplanet is a super-Earth, a world that is larger than Earth but smaller than Neptune. There are also planets like the ice giant Neptune, but smaller in size so they are called mini-Neptune. Astronomers have previously found that the atmospheres of some of these exoplanets have traces of water vapor, even on worlds with high temperatures and pressures.

“Young exoplanets usually harbor a hydrogen-rich atmosphere for the first few million years of their growth,” said Shahar. “Eventually these hydrogen shrouds dissipate, but they leave their mark on the composition of young planets.”

So instead of learning about exoplanets by studying Earth, Shahar’s team reversed the rules by treating Earth as an exoplanet to understand its early years, in a new way. Using findings from exoplanet studies, the team simulated a hydrogen shroud around the young Earth and studied what that shroud would mean for planetary evolution.

“What we found is that by treating Earth as an exoplanet (surrounded by hydrogen), we can explain many of Earth’s characteristics, including its water content,” said Shahar.

The Process of the Emergence of Water on Earth

For the research, they developed models to study 25 different compounds and 18 chemical reactions. They found large amounts of hydrogen from the atmosphere would mix with an ocean of molten magma on the lower surface, which then solidified to form Earth’s largest and thickest layer, the mantle. The planet’s abundant water reserves then formed as a simple consequence of these chemical reactions, they found.

The team said the movement of light molecular hydrogen from Earth’s atmosphere into its liquid interior early in Earth’s history answered two long-standing questions; How much liquid water appeared on Earth’s surface and why the planet’s core, which is mostly iron, is less dense than scientists think it should be.

“We’re learning something new about our own planet by looking at large exoplanet data sets. Answering questions from the lens of Earth science and astronomy is key!” said Shahr.

Of course this latest discovery does not necessarily make the asteroid theory, which is commonly used, no longer valid. The journey is still long, the theoretical and proving wars still have to be undertaken by scientists. So, let’s wait, which one makes sense. Source: Space.com