New research by The University of Manchester and the Carnegie Institution of Washington is to make scientists rethink their understanding of how Earth formed.
The team have found that volatile elements - most likely to include water - were present during the violent process of the Earth's birth between 30 and 100 million years after the solar system was created - a minute period in geological terms
The findings mean that comets and asteroids were unlikely to have brought the bulk of volatile elements to Earth - as commonly thought.
Lead scientist Dr Maria Schonbachler from The University of Manchester, publishes her research in Science, the prestigious weekly American journal today.
The scientist based at the University's School of Earth, Atmospheric and Environmental Sciences hit upon the findings by using high precision equipment to measure abundances of Silver isotopes contained in rocks.
The readings show that the moderately volatile element Silver was present in relatively large amounts towards the final stages of the Earth's formation.
The radioactive isotope Palladium 107 decays to Silver 107, which was present during the formation of the solar system.
The decay of Palladium 107 creates anomalies in the abundances of Silver isotopes, which can be measured and used for dating, even though Palladium 107 is no longer present on Earth.
The findings give a new boost to a 30 year old model, which suggests that volatile elements were already present in the final stages of the Earth's birth.
How much of these elements were lost during impacts like the one that formed the moon, however, is still not well known.
Dr Schonbachler said: "The sensitive equipment we use works in much the same way as when you might carbon date a rock or artifact - but on a scale which enables us to go back billions of years.
"And those measurements allow us to detect a transition from volatile-depleted to volatile-enriched building blocks as the accumulation of Earth proceeded.
"Because we know what happened to the moderately volatile Silver, it's very likely that the same thing happened to the highly volatile water.
"Though I accept that about 85 per cent of the Earth's mass was built without volatile elements the rest of it was- and that's quite an important difference in our understanding of the Earth's geological history."
"We don't now need any theories about how water came to Earth - such as comets and asteroids - it was most likely here almost from the beginning. And water is, what made Earth habitable for life. "
NOTES FOR EDITORS
Images are available
Dr Schonbachler is available for interview
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Journal
Science