Question: why is there no oxygen on different planets such as Mars, Jupiter, Saturn, Uranus, Neptune, Mercury and Venus apart from earth?

anon answered on 10 Nov 2016:

In the beginning, the Earth didn’t have an abundance of oxygen in it’s atmosphere like it does now. When plants started to evolve, they started photosynthesising, and converting carbon dioxide to oxygen. The reason we have so much oxygen in our atmosphere, but other planets don’t, is because we’re the only planet which has plants making new oxygen all the time.