A new study finds that, contrary to the popular theory that icy comets or asteroids delivered water to a newborn dry Earth, the planet itself may have produced its first water supply.
This water could have been the result of chemical reactions between a hydrogen-rich atmosphere, which researchers believe envelops the young Landand huge oceans of magma on the surface of the planet.
In these conditions, “water forms as a natural by-product of all the chemistry that’s going on,” study co-author Anat Shahar, a scientist at the Carnegie Institution for Science in Washington, D.C., told Space.com.
Related: How was the Earth formed?
Earth’s uniqueness in the solar system is due in part to its abundance of water It controls more than 70% of its surface, which is much more than any other planet in our cosmic neighborhood. However, when and where so much water came from remains an ongoing mystery to which scientists have not yet found a direct and conclusive answer.
One popular theory is that an asteroid impact is likely Delivered Most of the planet’s water, but some research has shown that water trapped inside asteroids is chemically different of water on the ground. Now, scientists say the abundant water supplies that made Earth the watery world it is today originated thanks to a hydrogen-rich atmosphere early in the planet’s history.
According to the latest study, local water would be the result if the size of the newly born Earth were 0.2 to 0.3 times the current size of the planet – slightly larger than previously thought. (The Earth, of course, continued to grow, accumulating more and more gases and dust around it.)
In this case, the young Earth would be massive enough to hold it atmospheres For a long time, it would have been much richer in hydrogen than the trace amounts we see today. (Earth’s current atmosphere is 78% nitrogen, while only hydrogen less than one part per million from the protective covering of the planet).
“Simply by changing the early conditions in which the Earth was formed, we can produce a lot of water that goes into the planet and into its atmosphere,” Shahar told Space.com.
Such hydrogen-rich atmospheres are regularly observed around many newly formed rocky exoplanets Solar System. The most common type of exoplanet Super Earth – Worlds larger than Earth but smaller than Neptune – called their smaller cousins the ice giant Mini Neptune. Astronomers previously found that the atmospheres of some of these exoplanets contain effects of water vaporeven in worlds with high temperatures and pressures.
young man outer planets They usually host hydrogen-rich atmospheres “during the first several million years of their growth,” Shahar said in a statement (Opens in a new tab). “Eventually these hydrogen envelopes dissipate, but they leave their fingerprints on the formation of the young planet.”
So instead of learning about exoplanets by studying Earth, Shachar’s team reversed the rule by treating Earth as an exoplanet instead to understand its early years in a new way. Drawing on results from exoplanet studies, the team simulated a hydrogen envelope around a young planet and studied what that might mean for the planet’s evolution.
“What we found is that by simply treating Earth as an exoplanet (surrounded by hydrogen), we were able to explain many of Earth’s properties, including its water content,” Shahar told Space.com.
For the study, the researchers developed a model to study 25 compounds and 18 different chemical reactions. They found that huge amounts of hydrogen from the atmosphere would have mixed with oceans of molten magma on the surface below, which then solidified to form the largest and thickest layer on Earth. cloak. They found that the planet’s abundant water reserves were a simple result of these chemical reactions.
The team says such movement of light hydrogen molecules from Earth’s atmosphere into its molten interior early in Earth’s history answers two long-standing open questions: How did large quantities of liquid water appear on Earth’s surface and why the planet’s core, which is mostly made of iron, Less dense than scientists think it should be.
“We learned something new about our own planet by looking at a large exoplanet data set,” Shahar told Space.com. “Answering the question from the lens of both Earth sciences and astronomy was key!”
the New study (Opens in a new tab) Published on Wednesday (April 12) in the journal Nature.
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