Mars Mars is the fourth planet from the Sun and the last of the solid and non-gaseous planets of our solar system. Mars is the seventh largest planet in our solar system. The diameter is approximately 4,220 miles. The equatorial circumference is approximately 13,259 miles. Earth's equatorial circumference is about 24,901 miles, so Mars' equatorial circumference is about 53.2% of Earth's. The radius of Mars' core is 1,056 miles. The surface area is 55,742,106 square miles, or about 28% of that of Earth. The volume of Mars is 163,115,609,799 cubic kilometers. The mass is approximately 641,693,000,000,000,000,000,000 kilograms. The average density of Mars is 3,933 kilograms/meter3. The average density provides clues to what the planet is made of, such as how much metal it contains and whether the planet is solid or gaseous (Mars Facts). Mars is made up of many different materials. The crust and surface are made up primarily of iron-rich basaltic rock, similar to the Earth's thin crust. The mantle is made of silicate rock and the core is probably made of iron, nickel and sulfur. Scientists are not sure, however, whether the core is hot liquid or cooled metal and whether there are two distinct layers like Earth's or not. The composition of Mars is similar to that of Earth. The main gases that make up the atmosphere of Mars are carbon dioxide (CO2), argon (Ar), nitrogen (N2), oxygen (O2) and carbon monoxide (CO). There is approximately 96% carbon dioxide, 1.93% argon, 1.89% nitrogen, 0.145% oxygen and less than 0.01% carbon monoxide. Mars' atmosphere also contains other gases in very small quantities, called trace gases. The atmosphere on Mars is about 100 times less dense than Earth's atmosphere (Mars Facts). The temperature on Mars is colder than on Earth because it is farther from the sun. According to scientists, temperatures and climates on Mars, that is, the possibility of people reaching the planet and surviving, are realistic. Mars One, a community of scientists who believe in this reality, has already begun taking applications for those wishing to take a one-way trip to Mars. They plan to start making these trips in 2024 (Human settlement of Mars). It may not seem realistic to be able to start a human settlement on Mars in just ten years, but it is possible. Work cited "Human settlement on Mars". Mars One. Mars One and Web. 09 May 2014."Exploration of Mars." National geographic. National Geographic and Web. May 7, 2014. "Facts about Mars." Mars Exploration Program Facts-Mars. NASA and Web. 01 May 2014"Mars: Moons." Exploration of the solar system. NASA and Web. 11 May 2014."The Moons of Mars." The moons of Mars. Np, nd Web. 07 May 2014.