How is our atmosphere different from the atmosphere on Venus and Mars?
Our atmosphere contains a mixture of many gases like nitrogen (78.08%), oxygen (20.95%), carbon dioxide (0.03%) and water vapour (in varying proportion). Whereas the atmosphere on Venus and Mars is mainly comprised of carbon dioxide. This carbon dioxide constitutes upto 95-97% of the atmosphere on Venus and Mars. It is supposed that, due to this reason no life is known to exist on these planets.
