Much of Earth's water predates the planet's creation. Image credit: NASA, Johns Hopkins University Applied Physics Laboratory, and Carnegie Institution of Washington.
New research has shown that water found on Earth is older than the Solar System.
The discovery raises hopes that life could evolve on other worlds.
The study set out to discover when the planet’s water originally formed, before it was deposited on the newly made Earth.
The international team of scientists found that a significant fraction of the water on our planet, and throughout our Solar System, predates the Sun.
This ancient water already existed in the cloud that gave birth to the Sun rather than forming later in the Solar System’s history.
As water can be ‘inherited’ from this environment, the team believes this means that other exoplanetary systems will also be rich in water.
“This is an important step forward in our quest to find out if life exists on other planets,” says Tim Harris from the University of Exeter, who was part of the research team.
“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.”
The team were able to work out when this water was created by using ‘heavy water’ ice – where the water contains the isotope deuterium rather than hydrogen – that has been found in asteroids and comets.
As these objects are left over from the Solar System’s formation, the team were able to show that a lot of the heavy water found today was inherited from the pre-existing environment.
“To date, the Kepler satellite has detected nearly 1,000 confirmed extrasolar planets,” says Ilsedore Cleeves, a PhD student at the University of Michigan.
“The widespread availability of water during the planet-formation process puts a promising outlook on the prevalence of life throughout the galaxy.”