Article Posted on : - Dec 12, 2009

Cracking the mystery of origing of life on Earth.

LONDON (PTI): Planetary scientists claim to have found evidence that the Earth's atmosphere and oceans which gave rise to life came from outer space probably on the back of comets or meteorites.

Previously it was thought that the gases and minerals were locked deep within the Earth's crust and only released in huge volcanic eruptions.

Now, a British team has proved that they must have come from outer space billions of years after our planet was first formed.

“We found a clear meteorite signature in volcanic gases. From that we now know the volcanic gases could not have contributed in any significant way to the Earth's atmosphere.

“The atmosphere and oceans must have come from somewhere else – possibly from a late bombardment of gas and water rich materials similar to comets,” The Daily Telegraph quoted Dr Greg Holland of University of Manchester as saying.

The team tested volcanic gases to uncover the new evidence. The scientists found they had chemical fingerprints matching that of meteorites rather than the inner Earth. The techniques enabled them tiny quantities of volcanic gases like Krypton and Xenon which revealed a chemical fingerprint matching that of meteorites.

Soon after it formed, the Earth's core was enveloped by an ocean of magma. Intense bombardment by meteorites combined with the core's heat to turn rocks into gases.

Within a few million years, a thick, dense atmosphere formed, even though a large portion of it was probably expelled by the gigantic impact that created the Moon 4.4 billion years ago.

“Many people have seen artist's impressions of the primordial Earth with huge volcanoes in the background spewing gas to form the atmosphere. We will now have to redraw this picture,” Professor Chris Ballentine of The University of Manchester, the project director, said.

The findings have been published in the latest edition of the journal Science.