|Mars, the fourth planet from the Sun|
|Aphelion||69,816,900 km (0.466697151 AU)|
|Semimajor axis||227,939,100 km|
|Orbital Period||686 days (1.87 years)|
|Average orbital speed||53,858 mph (24.077 km/s, 86,676 km/h)|
|Satellites||2 (Phobos, Deimos)|
|Surface area||144,798,500 km (0.284 earths)|
|Volume||1.6318×1011 km (0.151 earths)|
|Mass||6.4185×1023 kg (0.107 earths)|
|Surface temperature (min)||130 K (-225 °F, -143 °C)|
|Surface temperature (avg)||218 K (-67 °F, -55 °C)|
|Surface temperature (mean)||210 K (-81 °F, -63 °C)|
|Surface temperature (max)||308 K (95 °F, 35 °C)|
|Population||2 (Opportunity, Curiosity rover robots)|
|Surface Pressure||0.636 (0.4–0.87) kPa|
|Composition|| 95.32% carbon dioxide
2.7% nitrogen 1.6% argon 0.13% oxygen 0.08% carbon monoxide
|Habitable||Yes, with proper equipment.|
Mars is the fourth planet from the Sun, and the second smallest planet in the Solar System. Mars was named after the Roman god of war Mars, most likely due to it's reddish appearance in the sky. Mars is a terrestrial planet with a thin atmosphere. Mars is sometimes called 'earth's brother' because of their similar varieties of landscapes, with Mars having volcanoes, deserts, mountains, valleys, canyons, and Polar ice caps, like Earth. The rotational period and seasonal cycle is very similar (as the tilt of Mars produces seasons like Earth).
Mars is home to Olympus Mons, which is the tallest mountain in the Solar System. Mars is also home to Valles Marineris, one of the largest canyons. Mars has two irregularly and oddly shaped, small Moons, Phobos, and Deimos. These might actually be captured Asteroids rather then natural Moons.
Many people speculated that Mars would be similar to Earth in terms of oceans, liquid water, and more, until the first successful flyby in 1965, which showed that Mars did not have any sort of liquid water anywhere on it's surface (although it has been discovered that Mars did have oceans or at least lakes at some point in the past, though these have dissipated). Frozen water has discovered in the southern poles of Mars.
Mars is currently host to five functioning spacecraft: three of which are in orbit, and two on the surface. Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter are all orbiting Mars, while two rover robots, Opportunity, and Curiosity, roam the surface of the planet. Another rover robot, named Spirit, was a robot which became defunct in 2010 due to being stuck in soft soil. Other rover robots have become defunct as well, such as the Phoenix rover robot, which completed its mission in 2008.
A solar day (or sol) on Mars is slightly longer then an Earth day, a Martian day lasts 24 hours, 39 minutes, and 35 seconds.
Mars has approximately half the diameter of Earth. It is less dense then the Earth, having around only 15% of Earth's volume and only 11% of Earth's mass. Its surface area is only slightly less then the total of Earth's driest land.
Mars has a higher mass and is larger then Mercury, though Mercury has a higher density. This results in these planets having a nearly identical gravitational pull at the surface - that of Mars is less than 1%. The reddish-orangeish appearance of Mars surface is actually caused by iron(III) oxide, or more commonly known as hematite, or rust.
Like Earth, Mars has undergone differentiation, resulting in a dense, metallic core region overlaid by less dense materials. Current models of the planets interior imply a core region about 1794 km ± 65 km in radius, consisting primarily of iron and nickel, with about 16-17% sulfur. This iron sulfide core is partially fluid, and has twice the concentration of the lighter elements that exist at Earth's core.
Mars is a terrestrial planet that consists of minerals containing silcon and oxygen, metals, and other elements that typically make up rock. The surface of Mars is mostly composed of tholeiitic basalt, although parts of Mars are more silica-rich then the typical basalt and may be similar to andesitic rocks of the Earth or silica glass. Parts of the southern highlands include detectable amounts of high-calcium pyroxenes. Hematite and Olivine have also been found.