An llustration of water through time in the formation of the solar system. Photo: Bill Saxton/PA Wire

Water filling the earth’s oceans pre-dates the formation of the sun, increasing the chances of life emerging among the stars, scientists have revealed.

The discovery suggests that water may be a common ingredient in the clouds of dust and gas from which solar systems are born, and not ‘special’ to our own.

This has major implications for the likelihood of life being found on exoplanets orbiting stars beyond the sun. Tim Harries, from the University of Exeter, who took part in the research, said: “We know that water is vital for the evolution of life on earth, but it was possible that the earth’s water originated in the specific conditions of the early solar system, and that those circumstances might occur infrequently elsewhere.

“By identifying the ancient heritage of earth’s water, we can see that the way in which our solar system was formed will not be unique, and that exoplanets will form in environments with abundant water. Consequently, it raises the possibility that some exoplanets could house the right conditions, and water resources, for life to evolve.”

Some of the water in the solar system and on earth pre-dated birth of sun

The international team of scientists studied ancient ices preserved in comets and asteroids since the early days of the solar system.

Using sophisticated computer simulations, they were able to show that water in the oceans, meteorite samples and comets bore the chemical fingerprint of formation before the solar system took shape.

The water contained levels of deuterium − a ‘heavy’ strain of hydrogen with extra neutrons n its nucleus − that could only be explained by interstellar origins. It meant that at least some of the water in the solar system and on earth pre-dated the birth of the sun.

The findings are published in the latest issue of the journal Science. Lead author Ilsedore Cleeves, from the University of Michigan, the US, said: “The implication of these findings is that some of the solar system’s water must have been inherited from the sun’s birth environment, and thus pre-date the sun itself.”