After the Solar System formed, it took no more than three million years for the proto-Earth to finish developing its chemical composition, according to a new study from the Institute of Geological Sciences At that stage, however, the young planet contained almost none of the key ingredients for life, such as water or carbon compounds. Researchers conclude that only a later planetary impact likely delivered water to Earth, creating the conditions needed for life to emerge.
Earth remains the only planet known to support life, with both liquid water and a stable atmosphere. Yet when the planet formed, the environment was far from habitable. The gas and dust cloud that gave rise to the Solar System contained volatile elements essential for life, including hydrogen, carbon, and sulfur. But in the inner Solar System—where Mercury, Venus, Earth, Mars, and the asteroid belt reside today—these volatile substances could not easily survive.
The Sun’s intense heat kept them from condensing, leaving them largely in a gaseous state. Because they were not incorporated into the rocky material that built the planets, the proto-Earth ended up with very little of these crucial elements. Only celestial bodies forming farther from the Sun, in cooler regions, could accumulate them. The question of when and how Earth became a planet capable of supporting life remains unresolved.
Reconstructing Earth’s early chemistry
In their study, the Bern researchers demonstrated for the first time that the proto-Earth’s chemical makeup was fully established within three million years of the Solar System’s birth—but in a form that made life impossible. Their findings, published in Science Advances, indicate that a later event must have provided the missing ingredients that transformed Earth into a habitable world.
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