A group of scientists has proposed a new theory about how Earth's atmosphere got its oxygen: The planet slowed down and days got longer.A recent study proposes that longer, continuous daylight caused bacteria to produce lots of oxygen.That oxygen made most of life as we know it possible.The scientists dug up bad smelling, colorful bacteria from a deep sinkhole in Lake Huron, which is one of the Great Lakes in the northern United States.In laboratory experiments, the researchers gave the bacteria different amounts of light.They found that the bacteria produce oxygen at a higher rate the longer they receive continuous light.One of the great mysteries in science is how Earth went from a planet with little oxygen to the breathable air we have now.Scientists long believed that microorganisms called cyanobacteria were involved.
