Activity for RosesBouquet‭

Type	On...	Excerpt	Status	Date
Question	—	Is it feasible to have an oxidizing planetary atmosphere without the presence of an organic photosynthesis of some kind on the planet? With the emergence of cyanobacteria on earth 3.5 billion years ago, the shift from a reducing to an oxidizing atmosphere began. "The atmospheric O$\text{2}$ levels (in PAL; i.e., normalized to the present atmospheric level) would have risen mainly in two geological periods in the Earth history: th... (more)	—	almost 5 years ago