The thick organic fog that engulfed the early Earth several billion years agoit may have beensimilar to the haze that currently covers Saturn’s largest moon, Titan. That layer protected primordial life on our planet from the damaging effects of ultraviolet radiation.
Scientists at the University of Colorado at Boulder believe that Titan’s haze consists primarily ofmethaneYnitrogen, chemical by-products created by reactions with light. Not only is the fog the same one that protected the early Earth from ultraviolet light, but it would have allowed gases like ammonia to build up, causing warming bygreenhouse effect. And maybe that helped prevent the planet from freezing further.
The researchers determined that the hydrocarbon aerosol cloud was likely made up of soft microscopic particles that would have blocked UV light, but allowed visible light to reach Earth’s surface.
As part of studying the early Earth, Wolf and Toon used aclimate model from the National Center for Atmospheric Research that helps explain Titan’s strange haze, the second largest moon in the solar system and the largest moon of Saturn. Titan was the subject of intense study, following the arrival of the Cassini spacecraft at Saturn in 2004, allowing scientists to determine that it was the only moon in the solar system with both a dense atmosphere and liquid on its surface.
During the Archaic period, there was no ozone layer in Earth’s atmosphere to protect life on the planet, Wolf said. “The UV protection from the methane haze over early Earth would not only have protected the Earth’s surface, it would also have protected the gases in the atmosphere below it.” The researchers estimated that there was approximately 100 million tons of annual fog production in the early Earth’s atmosphere during thearchaic period. “If this were the case, an early Earth’s atmosphere would literally have produced a trickle of organic material into the oceans, providing manna from heaven so that the most primitive life could sustain itself,” Toon said.
