Water found in Earth’s oceans, in meteorites and frozen in lunar craters predates the birth of the solar system, a study published in this week's issue of the journal Science shows. The finding has 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.

To address the debate, researchers ran computer models comparing ratios of hydrogen with its heavier isotope, deuterium, which has been enriching the solar system’s water over time. In order 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 to have been formed before the sun’s birth, the scientists concluded. The process would probably be the same for other planetary systems as well, suggesting that conditions hospitable for life could exist beyond Earth.

IN-DEPTH

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Much of Earth's Water Is Older Than the Sun http://t.co/GDHMIWrGk9 pic.twitter.com/9zlBGXGO7Z — SPACE.com (@SPACEdotcom) September 25, 2014

Illustration of our Solar System's water through time, courtesy Bill Saxton, NSF/AUI/NRAO. http://t.co/jYHZBwl31m pic.twitter.com/vQLgsSdEen — Carnegie Institution (@carnegiescience) September 25, 2014

10-30 pct of Earth’s H2O prob came from comets outside our solar system --> we are 60 pct water --> we are all part alien http://t.co/yuW4rHXk0u — Kira Bindrim (@KiraBind) September 25, 2014

— Reuters