A new model suggests that up to half of the water on Earth may be older than the Sun and the rest of the Solar System. The model indicates that much of our planet’s water originated in the molecular cloud that created our Solar System, rather than the disc of material that was orbiting the Sun 4.6 billion years ago.

“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,” stated Ted Bergin, an astronomy professor at the University of Michigan who participated in the research.

“We let the chemistry evolve for a million years – the typical lifetime of a planet-forming disk – and we found that chemical processes in the disk were inefficient at making heavy water throughout the solar system. What this implies is if the planetary disk didn’t make the water, it inherited it. Consequently, some fraction of the water in our solar system predates the Sun.”

What this could mean is that water would be quite abundant in young solar systems since it doesn’t depend on the chemistry of the planetary disc, but what is in molecular clouds — making it easier, perhaps, for water to arise in planets.

The researchers’ work was published in Science.

Source: University of Michigan