Water on the Earth is older than the Solar System, according to a new study from researchers at the University of Michigan.
Astronomers have long questioned the origin of water on our home planet. Some believed the material formed in the rotating disk that created the Sun and the planets. Others theorized that the development of the life-giving material took place even earlier, in the molecular cloud that preceded the primordial disk.
Researchers analyzed data on the ratios of heavy water to the more familiar variety. Comets, left over from the formation of the solar system, contain these materials in proportions of the molecules different from the Sun. This study revealed that somewhere between 30 and 50 percent of water on our planet was formed in the ancient molecular cloud.
Astronomers created a simulation, recreating the formation of the Solar System. Starting the virtual model with no heavy water, they ran the program, attempting to find a scenario that produced the ratios seen in the real world now.
"Chemistry tells us that Earth received a contribution of water from some source that was very cold -- only tens of degrees above absolute zero, while the sun being substantially hotter has erased this deuterium, or heavy water, fingerprint," Ted Bergin, a professor of astronomy at the University of Michigan, said.
Astronomers who managed the study believe water on Earth and on worlds around the solar system started as tiny particles of ice, orbiting the Sun.
Astrobiologists believe that liquid water may be essential for the evolution of life, anywhere in the Universe. Analysis of the formation and development of water can assist researchers in their search for alien life on distant worlds.
Heavy water is composed of oxygen bound to atoms of deuterium, a form of hydrogen containing a neutron in their nucleus, together with a lone proton. This form of water is more common between stars than in the Solar System. This led many astronomers to believe there was heavy water between the stars, an idea borne out by the research. The simulation showed the early system could not have developed enough heavy water to account for current conditions; the material must have come in from outside.
"It provides the opportunity for organic materials, and the things that are important to the formation of life, to at least be accessible to all planets out there. Whether or not it forms into aliens and little green men and women is a whole other story," Fred Ciesla, a planetary scientist at the University of Chicago, told the press.
Analysis of water on the Earth and measurements of its age compared to the Sun was profiled in the journal Science.
