Water found in Earth’s oceans, in meteorites and frozen in lunar craters predates the birth of the solar system a finding with implications for the search for life on other planets.
Scientists have long debated whether the solar system’s water came from ice ionized during the formation of the solar system, or if it predated the solar system and originated in the cold interstellar cloud of gas from which the sun itself was formed.
A study was published in issue of the journal Science.
“It's remarkable that these ices survived the entire process of stellar birth,” lead researcher Lauren Cleeves.
Cleeves, a doctoral student at the University of Michigan, had been studying how radioactivity, galactic cosmic rays and other high-energy phenomena impact planet-forming disks of matter that circle young stars.
“Without any new water creation, the only place these ices could have come from was the chemically rich interstellar gas out of which the solar system formed,” she said.
To prove the point, she and colleagues ran computer models comparing ratios of hydrogen with its heavier isotope, deuterium, which has been enriching the solar system’s water over time.
To reach the ratios found in meteorite samples, as well as in Earth's ocean water and comets, at least some of the water would have had to be formed before the sun’s birth, the scientists concluded.
The process likely would be the same for other solar systems as well, suggesting conditions hospitable for life could exist beyond Earth.