Hazy skies on early Earth, similar to those on Saturn’s moon Titan, could have provided the material needed to form life, according to a new study.

Titan has a thick hazy layer of substances known as organic aerosols, carbon-based chemicals related to the ingredients of living things.

These compounds are believed to be generated from chemical reactions of molecules of methane and nitrogen high in Titan’s atmosphere, stimulated by the sun’s ultraviolet rays.


Two lakes on Titan, containing what scientists believe is a mix of carbon-based substances ethane and methane. The radar image comes from the Cassini-Huygens mission, a collaboration of NASA, the European Space Agency and the Italian Space Agency.

Margaret Tolbert of the University of Colorado at Boulder and colleagues mimicked Titan’s chemistry by using ultraviolet lamps in various simulated atmospheres.

The researchers found that a methane-nitrogen mix would produce various types of large molecules known as long-chain hydrocarbons.

These, they reported, matched some of the known compounds observed by Huygens, a European-built probe that dropped onto the smog-shrouded world last year.

The researchers also tested atmospheres that might have resembled early Earth, containing methane and carbon dioxide. These conditions gave rise to a haze containing a different but related set of long-chain compounds, including chemicals known as aldehydes and ethers, they said.

The researchers calculate that Earth could have produced over 100 million tons of such material each year, and it could have served as the primary source material for primitive life. The findings are published in this week’s early online edition of the research journal Proceedings of the National Academy of Sciences.


- Courtesy PNAS
and World Science staff

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