How does Earth's atmosphere compare to the atmospheres of Mars and Venus?

Okay first of all mars does not have life 2ndly mars is the 4th planet earth is the 3rd planet mars is mostly red and earth is mostly blue there is some but there are alot more

The difference between them is that Earth is larger and Mars does not have qualities for life to sprout.

71% of Earth's surface is water. Mars has no liquid water, but the Phoenix Mars Lander scooped up soil and ice.

Mars gravity is 2.7 times less than that of Earth. Mars has 2 moons and it's atmosphere is 95% CO2 with a tiny bit of nitrogen, argon, oxygen, and carbon monoxide.

Earth has 1 moon and has a lot of nitrogen and some oxygen and others (tiny bits of argon and carbon dioxide).

(Also, our deserts are hot in the daytime and cold at night. Mars's deserts are freezing and airless.)

The biggest difference is that Earth has advanced life forms, Mars does not.

Mars is smaller than earth with less gravity. It also has a very thin CO2 atmosphere where Earth has a Nitrogen Oxygen atmosphere that is much thicker. Mars is also very cold while Earth is warm.

* Earth is almost twice the diameter of Mars.

• Nearly 70% of Earth's surface is liquid water, while Mars has none.
• The sun warms the Earth to more the 100oF; on Mars the temperature barely goes above the freezing mark.
• Earth has an atmosphere breathable by humans. Mars has virtually none, and it is composed almost entirely of toxic gases.

  IIRC, Mars is about 1 1/2 time farther from the sun than Earth; and is about 1/2 the size, and 3/4 the density.

  It's surface is largely iron oxide, which gives it its reddish color. There is no liquid water (there is ice at the poles). Because is it has a much thinner atmosphere, and is farther from the sun, it is much colder.

  Astronmers speculate that Mars was once much closer to the sun and was more "earthlike," but gradually moved farther away, resulting in its present state.