Tuesday, November 07, 2006

Cloudy Skies Rained Life

Hazy skies on early Earth could have provided a substantial source of organic material useful for emerging life on the planet.
From the press release:

Researcher have measured the organic particles produced from the kind of atmospheric gases thought to be present on early Earth. They modeled conditions measured by the Huygens probe on Saturn's moon, Titan, last year during the Cassini mission. They mimicked Titan's hazy skies by exposing methane gas to an ultraviolet lamp, then added carbon dioxide gas to the mix to see if conditions that were probably present on early Earth would produce a similar organic haze. "It turns out that organic haze can form over a wide range of methane and carbon dioxide concentrations," said Tolbert.

"This means that hazy conditions could have been present for many millions or even a billion years on Earth while life was evolving."

"We found that you can make a lot of organic material virtually out of thin air," said Trainer.

According to the study, a similar haze hanging over Earth early in its history could have supplied more than 100 million tons of organic material to the planet's surface each year. "As these particles settled out of the skies, they would have provided a global source of food for living organisms," said Trainer.

In addition to serving as a source of organic material, a haze layer over Earth could have shielded living organisms from harmful UV rays and helped to regulate Earth's early climate, according to the study.

The paper will be up shortly at the PNAS.org early editions page.