Both Venus’s and Mars’s atmospheres are mostly comprised of carbon dioxide. Venus has at atmosphere that contains about 96% carbon dioxide, 3.5% nitrogen, and the remaining 0.5% is made up of water vapor, sulfuric acid, hydrochloric acid, and hydrofluoric acid. Mars’s atmosphere is made up of 95% carbon dioxide, and a few percent each of both nitrogen and argon. Evidence shows that both Venus and Mars used to have water but now Venus is extremely dry and contains no water at all. Water can only exist as ice or vapor on Mars and the atmosphere contains very little water vapor or oxygen. Venus’s atmosphere contains very high and stable clouds that move quickly and carry heat uniformly throughout the planet. Mars is Essentially, the major
