Up to half of the molecules in Earth's water predates the Sun by 4.6 billion years, suggests a new research paper published Thursday in the journal, Science.

That makes water in the Earth's oceans older than the Earth, the solar system and the Sun.

Earlier research suggested that water was delivered to the planet after its birth through an intense bombardment of water-rich comets. Other competing theories proposed that water formed as the result of the oxidation of an atmosphere rich in hydrogen.

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Researchers at the University of Michigan, however, chose to look further back in time.

Rather than asking how water came to exist on Earth, astronomy PhD student Ilse Cleeves and her colleagues investigated how water came to the solar system.

Cleeves developed a model that traced a modified form of hydrogen called deuterium. By studying the ratio of the hydrogen and deuterium content in Earth's water, scientists were able to identify how exactly water was formed and what the circumstances were surrounding its formation.

Scientists have long known there was water before the Sun was born, but until now have believed that the hot, violent process of the Sun's formation destroyed it. What was left turned into a form of matter called the protoplanetary disk from which all plants formed and from which new water was produced.

The new study explained that the solar system was actually able to retain the water it inherited prior to the formation of the Sun. Some 30 percent to 50 percent of the Earth's water predates the Sun, the study suggests.

Beyond probably settling the debate of how Earth's water was formed, the study suggested that its findings have some universal implications.

If this research is correct and if water, indeed, survived the trauma of the Sun's formation, this means that water is available at the birth of planets.

Thus, the same molecule that gave birth to life on Earth may also be found in other planetary systems.

TagsEarth, Earth's water, water formation, new study