Water in Earth's oceans older than the sun

WASHINGTON, Sept. 25 (UPI) -- If you took a dip at the beach this summer, chances are you bumped up against some truly ancient water molecules -- water older than the sun. In fact, there's probably interstellar water hanging out inside all of us -- we are 60 percent water, after all.

A new study suggests as much as a third of Earth's ocean water was likely formed prior to the birth of the sun and sourced from deep space ice.

Like all planets in our solar system, most of the Earth and much of its water was formed from the debris floating around our young sun -- a hot cloud of gas and other cosmic material known as the solar nebula. Included in this nebula were ices, but we know there are also ices floating in interstellar space -- as evidenced by meteorite samples.

What scientists haven't been sure of, however, is exactly how much of our water is made of interstellar ice, and how much was formed locally in the solar nebula. To solve that quandary, a team of scientists led by L. Ilsedore Cleeves from the University of Michigan built a model to predict the answer. The model was based on the scientists' understanding of the chemical circumstances that enable the formation of "heavy" water molecules -- a molecule with a deuterium atom instead of a hydrogen atom.

About 1 in every 3,000 water molecules has a deuterium atom. The scientists' model, part chemistry part mathematics, showed that the solar nebula wasn't capable of forming all of Earth's heavy water on its own, and thus suggested roughly a third of Earth's water is really alien water.

"Our findings show that a significant fraction of our Solar System's water, the most-fundamental ingredient to fostering life, is older than the Sun, which indicates that abundant, organic-rich interstellar ices should probably be found in all young planetary systems," said Conel Alexander, a researcher at Carnegie Science institute in Washington.

As Alexander explained, the revelation suggests the materials necessary for life are probably not as rare as scientists previously thought.

"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," Alexander added.

The study was published this week in the journal Science.