Cosmic Dust on Earth Reveals Clues to Ancient Atmosphere

The oldest space dust yet found on Earth suggests that the ancient atmosphere of Earth had significantly more oxygen than previously thought, a new study finds. Although oxygen gas currently makes up about one-fifth of Earth's air, there was at least 100,000 times less oxygen in the primordial atmosphere, researchers say. Previous research suggests that significant levels of oxygen gas started permanently building up in the atmosphere with the Great Oxidation Event, which occurred about 2.4 bill