Mars' atmosphere is also made of Iron oxide, which reacts with the Carbon Dioxide/CO2 to make the planet red.

There are 8 planets and over 160 moons in the solar system. The atmosphere of Mars is the layer of gases surrounding Mars.It is primarily composed of carbon dioxide (95.32%), molecular nitrogen (2.6%) and argon (1.9%). However, Venus has about 154,000 times more carbon dioxide in its atmosphere than Earth (and about 19,000 times more than Mars does), producing a runaway greenhouse effect and a surface temperature hot enough to melt lead. Atmosphere - Atmosphere - The atmospheres of other planets: Astronomical bodies retain an atmosphere when their escape velocity is significantly larger than the average molecular velocity of the gases present in the atmosphere. It also contains trace levels of water vapor, oxygen, carbon monoxide, hydrogen and other noble gases. Venus, on the other hand, has more Carbon Dioxide because it is hotter and more gassy and poisonous. Smog composed of ethane is present high in the atmosphere. Of these, the planets Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune have significant atmospheres. Plants and other photoautotrophs use solar energy to produce carbohydrate from atmospheric carbon dioxide and water by photosynthesis. Mars’ Atmosphere: Planet Mars has a very thin atmosphere which is composed of 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water.

Planet; The atmosphere is mostly carbon dioxide. The planet's small size means its gravity is too weak to hold much of an atmosphere. The atmosphere of Mars is more than 96% carbon dioxide, but the planet is cold because its atmosphere is extremely thin, very dry and further away from the Sun.

Carbon is the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen.. Marc Kuchner and Sara Seager coined the term "carbon planet" in 2005 and investigated such planets following the suggestion of Katharina Lodders that Jupiter formed from a carbon-rich core.
A carbon planet is a theoretical type of planet that contains more carbon than oxygen. Blue-green color of atmosphere is due to the absorption of red wavelengths by methane.

Venus’ atmosphere, like Mars’, is nearly all carbon dioxide.
Carbon dioxide (CO 2) is an important trace gas in Earth's atmosphere.It is an integral part of the carbon cycle, a biogeochemical cycle in which carbon is exchanged between the Earth's oceans, soil, rocks and the biosphere. It can linger in the atmosphere for thousands of years .

Carbon dioxide (CO 2): Carbon dioxide is the primary greenhouse gas, responsible for about three-quarters of emissions. CO2 gives off alot of gas, it is a bit poisonous (in large quantities), and sometimes can be hot if reacted with the right chemicals, and those chemicals might be on Venus. Atmospheric pressure at the surface is less than one-trillionth … Thick clouds of nasty sulfuric acid completely cover the planet.