Ancient Earth was Oxygen-Rich

                Earth’s upper atmosphere contained about same amount of oxygen 2.7 billion years ago as today, according to new surprise finding that challenges the accepted view of our planet’s atmosphere. The researchers used the oldest fossil micrometeorites – space dust – ever found to the make the discovery about the chemistry of the Earth’s atmosphere. The finding show that the ancient Earth’s upper atmosphere contained about the same amount of oxygen as today, and that a methane haze layer separated this oxygen-rich upper layer from the oxygen-starved lower atmosphere.