The 8 Planets – Part 4: Mars



A very belligerent planet. Mars. Named after the Roman god of war, Mars appears as a fiery battle-stained planet. Out of the seven planets (excluding Earth), Mars seems to be the most habitable planet. Although much smaller than Earth, Mars has an atmosphere (though thinner), ice caps (though mainly dry ice, or frozen carbon dioxide), and evidence that water once flowed on its surface. Astronomers have yet to find life on Mars, but sci-fi authors have long contemplated the possibility of life on Mars in the present or future (e.g. The Martian Chronicles). Don’t let the name fool you. Mars, the god of war, leaves no one alive while Venus, the goddess of love, often has a soft heart. In the solar system, Venus is a deadly planet while Mars is relatively benign.

The fourth planet from the Sun and the last terrestrial planet, Mars, the “Red Planet,” is actually the second smallest planet and the most explored aside from Earth. Distinguishable by its red color from an abundance of iron oxide, Mars has a thin atmosphere blanketing a surface filled with impact craters, volcanoes, valleys, deserts, and polar ice caps. Mars is also home to Olympus Mons, the tallest mountain in the solar system, and Valles Marineris, a large crack on Mars’ surface and one of the largest canyons. Dark patches on its surface suggest presence of large quantities of liquid water in the past. Though similar to Earth in surface features and climate, Mars is only about half the size of Earth, with 15% of Earth’s volume and 11% of mass. Because of its similar axial tilt, Mars has Earth-like seasons, though with a colder climate. Barren, Mars has the largest dust storms in the solar system. Mars is bigger than Mercury but less dense because of an iron sulfide core composed of lighter elements. The core is surrounded by a silicate mantle and the mantle by a thick crust. With no evidence of a global magnetic field, Mars, however, has some magnetized crust that has reversed polarity like Earth’s ocean floors. Mars’ geological history is split into three periods: Noachian period (4.5 – 3.5 billion years ago, oldest surfaces with impact craters and extensive flooding of water), Hesperian period (3.5 to 2.9 – 3.3 billion years ago, extensive lava plains), Amazonian period (2.9 – 3.3 billion years ago to present, few impact craters, Olympus Mons forms, lava flows). On Martian Soil, light silica-rich streaks appear on steep slopes, perhaps the dark underlying layers of soil exposed after dust avalanches. As Earth speeds Mars, Mars appears to move in a retrograde motion, or backwards with respect to the stars. Mars has two moons: Phobos and Deimos.


Phobos and Deimos

Mars’ two moons look more like asteroids than Earth’s moon. Named for Mars’ sons and attendants in battle, Phobos and Deimos mean “fear” and “panic,” respectively. Because of their low albedo, carbonaceous chondrite composition, and irregular shapes, scientists have proposed the capture theory. Stray asteroids from the Trojan belt may have been pulled into Mars orbit. Phobos is below synchronous position, so Mars’ tidal forces will eventually cause Phobos to crash into Mars’ surface, either forming an impact crater or a dust ring in 50 million years. On the contrary, Deimos is outside synchronous position, so the moon is slowly spiraling away from Mars. In about 50 million years, Mars may have no moons!

MISSIONS*: Mariner, Mars, Viking, Mars Global Surveyor, Mars Pathfinder, Mars Odyssey, Mars Express, Spirit, Opportunity, Rosetta, Mars Reconnaissance Orbiter, Phoenix, Dawn, Mars Science Laboratory

* Successful Missions


  • Order in Solar System: #4
  • Number of Moons: 2
  • Orbital Period: 687 days
  • Rotational Period: 24 hours, 39 minutes, 35 seconds
  • Mass: 6.4185 x 10^23 kg (0.107 Earths)
  • Volume: 1.6318 x 10^11 km³ (0.151 Earths)
  • Radius: 3,396 km (0.533 Earths)
  • Surface Area: 1.45 x 10^8 km² (0.284 Earths)
  • Density: 3.9335 g/cm
  • Surface Pressure: 0.636 kPa
  • Eccentricity of Orbit: 0.093315
  • Surface Temperature (Average): 210 K
  • Escape Velocity: 5.027 km/s
  • Apparent Magnitude: +1.6 to -3.0

Fun Facts Cluster 1: 16 Extreme Space Facts (NASA)

NASA: Extreme Facts

“16 eXtreme space facts!”

By: NASA (

-The following is from NASA’s informational guide (shown above) on astronomy facts.

  1. Better stick with a rubber ducky: Saturn is the only planet in our solar system that is less dense than water. It could float in a bathtub if anybody could build a bathtub large enough.
  2. Fastest: True to its namesake (the speedy messenger of the Roman gods), Mercury is the fastest planet in our solar system. It zips around our Sun at an average of 172,000 kilometers per hour (107,000 miles per hour) — about 65,000 kph (40,000 mph) faster than Earth. A year on Mercury is equal to 88 Earth days.
  3. Biggest and smallest: Ceres if the largest, most massive body in the main asteroid belt between Mars and Jupiter, totaling about a third of the total mass of the entire belt. But Ceres is the smallest of the dwarf planets, which include Pluto and Eris, and the only dwarf planet that resides in the asteroid belt.
  4. Forget the socks, bring a hat: If you could stand at the Martian equator, the temperature at your feet would be like a warm spring, but at your head it would be freezing cold!
  5. It’s a small world after all: More than 1,300 Earths would fit into Jupiter’s vast sphere.
  6. Chill out!: Craters at the Moon’s south pole may be the frostiest locale in the entire solar system. In the permanently shadowed crater floors, “daytime” temperatures may never rise above minus 238 degrees Celsius (minus 397 degrees Fahrenheit).
  7. Windiest: Neptune’s winds are the fastest in the solar system, reaching 2,575 kilometers per hour (1,600 miles per hour)! Neptune’s giant, spinning storms could swallow the whole Earth.
  8. Tiny, very tiny: The radio signal that some spacecraft use to contact Earth has no more power than a refrigerator, light bulb. And by the time the signal has traveled across space, the signal may be only one-billionth of one-billionth of one watt!
  9. Big, way big: To detect those tiny signals from space, the Deep Space Network uses dish antennas with diameters of up to 70 meters (230 feet). That’s almost as big as a football field.
  10. Not much!: If you could lump together all the thousands of known asteroids in our solar system, their total mass wouldn’t even equal 10 percent of the mass of Earth’s moon.
  11. Easy does it: A Venus day is approximately 243 Earth days long. The bad news is we would have to wait up to three Earth years for a weekend. That’s because a day on Venus is longer than its year!
  12. Pizza?: Jupiter’s moon Io if the most volcanically active body in our solar system. The moon’s bizarre, blotted yellowish surface looks like a pepperoni pizza!
  13. Air Martian: The gravity on Mars is approximately one-third that on Earth. Yes, chances are you’d be able to dunk the basketball on a Martian court.
  14. Skating, anyone?: If you ice skate, how about Europa? Europa is one of the four largest moons of Jupiter. It’s a little smaller than Earth’s Moon. Europa is covered in ice, including some smooth ice! A 3-foot (about 1 meter) Axel jump on this moon would take you 22 feet (more than 6 meters) high, with the same landing speed as on Earth.
  15. Grandest Canyon: The largest canyon system in the solar system is Valles Marineris on Mars. It’s more than 4,000 kilometers (3,000 miles) long — enough to stretch from California to New York. It is nine times as long and four times as deep as Earth’s Grand Canyon!
  16. Sizzling Venus: The average temperature on Venus is more than 480 degrees Celsius (about 900 degrees Fahrenheit) — hotter than a self-cleaning oven.