Mars Earth Consequence of difference Gravity 1/3 that of Earth(3.7 m/s2) 1.0 (9.8 m/s2) Because of Mars' lower gravity, we would walk with a light "bounce". Diameter 4200 miles 7900 miles Since Mars is small and not as dense as Earth, it does not have a large amount of internal heat. This contributes to why it is cold and dry today. Average distance from Sun 141,000,000 miles 93,000,000 miles Mars receives, on average, about 44% of the sunlight received on Earth. Orbital eccentricity 0.093 0.017 Seasons are of unequal length. Mars is closest to the Sun in southern summer/ northern winter, and furthest in southern winter/northern summer. The southern hemisphere has shorter, warmer summers and longer, colder winters. During southern summer, dust storms often circle the entire planet. One day 24 hours 37 minutes 23 hours 56 minutes Remarkably similar length of day between Earth and Mars requires little internal biological adjustment of people who would live on Mars. One year 687 days 365.25 days While Martian seasons are of unequal length, each one is about twice as long as seasons on Earth. Atmospheric pressure 6 to 9 millibars or 0.15 lb/in2 1013 millibars or 14.7 lb/in2 The Martian air is extremely thin. On Mars, people must live in pressurized dwellings and wear pressure suits with air tanks in order to walk outside. Atmospheric components 95% carbon dioxide 3% nitrogen ~2% other gases ~0 oxygen 77% nitrogen 21% oxygen 0.04% carbon dioxide 2% other gases The air on mars is unbreatheable for humans. Protection from harmful radiation? No Yes Mars' atmosphere is too thin to protect the surface from harmful ultraviolet radiation and cosmic rays. Average temperature range +40°F to -135°F +95°F to -35°F Mars has a greater daily temperature change than Earth does, making properly functioning temperature regulation systems very important. Moons Two One Mars' two tiny moons, Phobos and Deimos could provide staging locations for exporting Martian minerals to Earth. Explanation of terms Gravity - The amount of force that a body, such as a planet or a moon, pulls on another object. Diameter - The width of an object. Orbital eccentricity - Planet orbits are not perfectly circular but are slightly oval-shaped. "Orbital eccentricity" refers to the amount of "oval-ness" of the orbit. A higher eccentricity value means a planet's orbit is more oval-shaped. The planet is further from the Sun at one point in its orbit and closer to the Sun at another point. One day - The amount of time it takes for an object, such as a planet, to rotate, or turn, once. One year - The amount of time it takes for a planet to revolve, or go around the Sun, once. Atmospheric pressure - The amount of air, or atmosphere, a planet or moon has. At sea level on Earth, 14.7 pounds of air pushes on every square inch of every object. This means that the average human has about one ton of air pushing on his or her entire body. On Mars, the average human would have about one-tenth of one pound of air pushing on his or her entire body. Atmospheric components - The contents of a planet's or moon's atmosphere. Average temperature range - The average high summer temperature and the average low winter temperature. Moon - Natural satellite orbiting a planet.