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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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ScienceShot: An Atmospheric Flip-Flop
18 March 2012 2:00 pm
About 2.45 billion years ago, Earth might have been confused for Titan. Research published today in Nature Geoscience suggests that our planet had the same hazy, methane-rich atmosphere as Saturn's largest moon (pictured). Scientists analyzed 2.65-billion- to 2.5-billion-year-old sediments from South Africa in order to reconstruct past ocean and atmosphere chemistry. They were surprised to find that, rather than a single, consistent past atmospheric state, Earth flip-flopped between "organic haze," or hydrocarbon smog, and "haze-free" conditions. Methane-producing microbes in the ocean, the researchers say, drove these cycles. Some oxygen was being produced by other seafaring microbes, but little of it reached the atmosphere. It was not until about 100 million years later that photosynthetic organisms known as cyanobacteria dominated the seas and injected massive amounts of oxygen into the atmosphere, creating conditions similar to those we enjoy today.
See more ScienceShots.