Where did the building blocks of Earth's first water come from?🧐 Water is made up of two hydrogen atoms and one oxygen atom, and rocky asteroids likely carried most of that hydrogen to Earth billions of years ago.
However, the new research suggests that young Earth also received hydrogen from the solar nebula.
In the early solar system, this cloud — the material leftover after the sun's formation — contained large amounts of hydrogen.
The ratio of normal hydrogen and deuterium — a heavier isotope — in ocean water matches the ratio found in water from asteroids, suggesting that Earth's water had asteroid origins.
However, hydrogen extracted from the planet's interior, near the region where the mantle meets the core, tells a different tale.
Those samples had less deuterium than hydrogen compared with ocean water, pointing to a source other than asteroids, according to the study.