Does Mars have an atmosphere? Yes, Mars does have an atmosphere. The Martian atmosphere contains about 95.3% carbon dioxide (CO2) and 2.7% nitrogen, with the remainder a mixture of other gases. However, it is a very thin atmosphere, roughly 100 times less dense than Earth's atmosphere. Note: If Mars did not have an atmosphere images taken from the surface of Mars (like the one to the right) would show a black sky, even during the day.