Mars Diameter: 4220 miles (roughly half of Earth's, close to Titan's size, twice Luna's)

Mars Solar Year: A solar year on Mars is 687 Earth days

Mars Day Length (or "SOL"): About 24.6 hours

Minimum Mars-Earth distance: 54.6 million km

Average close approach to Earth: 0.3727 AU (55.76 million Km)

Next close approach: 31 July, 2018

Last close approach: 30 May 2016 (happens about every 26 mo.)

Climate: Cold and dry! Temps warmer at equator, but vary: -284 F (-140 C) to +86 F (30 C)

Weather: Winds and seasonal dust storms despite a thin atmosphere; Mars has trace water vapor

Water: Arid climate's low pressure and triple point means liquid water not as common as permafrost

Hydrated salt water has been detected at Hale Crater by NASA MRO using HIRISE imaging and sensors

Mass: About 1/10th that of Earth

Gravity: Low, roughly 0.375 Earth's gravity

Land mass: Almost as much as Earth's dry land

Atmosphere: Thin, but mainly 96% CO2, 2.7% N, 1.6% Argon, < 1% other with trace Oxygen

Very different from Earth's air components: 0.04% CO2, 78.09% N, 20.95% O2, 0.93% Argon, water vapor and other traces)

Mars Moons:

• Phobos (22.2 km diam), orbits at 1.4 Mars diameters, period 7.6 hr
• Deimos (12.6 km diam), orbits at 3.5 Mars diameters, period 30.3 hr

Mars 7 Known Trojan Asteroids (at Lagrangian pts):

• L4 (leading): "(121514) 1999 UJ7"
• L5 (trailing): "5261 Eureka" and 5 others

Mars Orbit: Quite elliptical, eccentricity = 0.0934

Perihelion = 1.381 AU, Aphelion = 1.666 AU

Mars averages about 142 million miles from the Sun, some 50% farther out than Earth

(1 AU = Astronomical Unit, standard Sun-Earth distance)

Orbital Tilt: 25 deg (vs 23.5 deg Earth) => Seasons, but longer, warmer in Northern Mars