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ANN ARBOR, Michigan — Half of the water on Earth may be a million years older than the solar system, according to a new study.
The water came from interstellar ice in the molecular cloud that gave birth to the sun and planets in this solar system, according to the study published Friday in the journal Science. Researchers estimated between 30 and 50 percent of water in the solar system originated from the molecular cloud.
“Why this is important? If water in the early solar system was primarily inherited as ice from interstellar space, then it is likely that similar ices, along with the prebiotic organic matter that they contain, are abundant in most or all protoplanetary disks around forming stars,” said University of Michigan researcher Conel Alexander in a statement.
To determine the origin of Earth’s water, researchers said they simulated the chemistry that occurred during the formation of the solar system and examined the ratio of hydrogen to deuterium in water molecules.
"We let the chemistry evolve for a million years — the typical lifetime of a planet-forming disk — and we found that chemical processes in the disk were inefficient at making heavy water throughout the solar system," researcher Ilse Cleeves said in a statement. "What this implies is if the planetary disk didn't make the water, it inherited it. Consequently, some fraction of the water in our solar system predates the sun."
The findings suggest “abundant, organic-rich interstellar ices should probably be found in all young planetary systems,” according to Alexander.