The ultimate guide to planet mars


Mars is the most explored planet in the solar system with every world’s every space agency wanting to explore the Red planet.

Let us see what makes this planet so special that everyone wants their hands laid on it.

The planet Mars is the fourth planet from the Sun and the second smallest after Mercury. It is the last of the terrestrial planet made up of the rocky surface.

A little history

Mars is named after the Greek god of war Ares. Romans then did the likewise by naming it after their god of war mostly because of the red colour of the planet.

Chinese called it ‘the fine star’, Egyptians called it ‘the red one’ and Indians ‘Mangal’.

Sumerians first thought that the planet was a star. Greek astronomer Ptolemy made some significant research on the planet.

Indian astronomical text Surya Siddhanta estimated the diameter of Mars.

Galileo Galilei was the first person to observe the planet through the telescope.

Distance from the Sun

Mars is the fourth planet from the Sun. With an average distance of 142 million miles (228 million km), Mars is about 1.5 astronomical units away from the Sun.

Mars makes its closest approach to the Sun (Perihelion) at 128 million miles (206 million km) and farthest (Aphelion) at 154 million miles (249 million km).

It takes Sunlight 13 minutes to reach from the Sun to Mars. From the Mars surface, the Sun will appear about half the size than it does on Earth.

At its closest point to the Sun the Martian southern hemisphere leans towards the Sun, causing a short, intensely hot summer, while the northern hemisphere endures a brief, cold winter.

At its farthest point from the Sun, the Martian northern hemisphere leans towards the Sun, causing a long, mild summer, while the southern hemisphere endures a long cold winter.

Size of Mars

Mars is the second smallest planet in the solar system behind Mercury and is about half the size of the Earth.

Mars size compared to Earth
Mars compared to Earth

With a diameter of 6700 km, Mars has about 38 % of the surface area of Earth which is equal to the total dry land on Earth, since most of the Earth is covered in water.

The volume of Mars is 15% of Earth’s surface and mass is 11% of Earth.

Orbit and rotation

Mars is roughly 142 million miles (228 million km) from the Sun.

It takes Mars 687 Earth days to make one full rotation around the Sun which is equal to 1 year, 320 Earth days.

One day on Mars is 24 hours 40 minutes which is similar to Earth’s 24 hours.

Mars has an axial tilt of 25.19 degrees which is similar to Earth, as a result, Mars also experience seasons like Earth. Although seasons on Mars are twice as long because it’s orbital period id much larger.

Mars has an orbital eccentricity of 0.09 which is the second largest only behind Mercury. This eccentricity results in a more elliptical orbit.


Mars has a very thin atmosphere similar to Mercury.

The Martian atmosphere is made up of 95% Carbon dioxide (CO2), 27% Nitrogen (N), 1.6% Argon (Ar), 0.2% Oxygen(O2) and trace amounts of water vapor and carbon mono oxide.

Venus is also made up of 97% Carbon dioxide but because of its thick atmosphere temperature on Venus can spike up to 480 degrees Celsius. But the temperature on Mars hardly goes over 20 degrees Celsius. This is because of Mars very thin atmosphere which doesn’t trap the Sun’s heat.

The temperature on Mars can go as high as 20 degrees Celsius or as low as -153 degrees Celsius.

The atmospheric pressure of Mars is only 1% of that found at the sea level on Earth.

It is not possible for liquid water to exist on the planet’s surface, however liquid water might exist below the planet’s surface.

Many theories suggest that Mars once had a thick atmosphere and flowing water, but the process was altered for some reason. The most popular explanation for this change is that Mars was struck by a large body which resulted in the planet’s debris flowing into space.

Mars experiences pretty strong winds creating dust storms that can cover the entire planet. This type of storms can last for months.

Methane has been detected in the Martian atmosphere. Methane might be produced by a non-biological process such as serpentinization or by Methanogenic microbial life.

Possible Methane sources on Mars
Possible Methane sorces on Mars


In December 2014, NASA’s MAVEN detected auroras in Mars northern hemisphere. The phenomenon is created when the protons from the solar wind hit the thin Martian atmosphere exciting the gas particles and making it glow.


Mars has no rings. However, astronomers predict that Phobos might crash into Mars in about 50 million years, which might create a dusty ring around the Planet.

Now imagine Mars with rings… Sounds cool…

Related: Exploring planet Saturn and its elegant rings


The main reason why Mars looks reddish is because of the oxidization or rusting of iron in rocks and dust of Mars.

Mars is thought to be about 4.603 billion years old.

The geological history of Mars can be split into three main periods:

  • Noachian period: Formation of the oldest extant surfaces of Mars, 4.5 to 3.5 billion years ago. The Noachian surface is scarred by many largest impact craters. The Tharsis bulge, a volcanic upland, is thought to be formed during his period, with extensive flooding by liquid water during this period.
  • Hesperian period: 3.5 to between 3.3 and 2.9 billion years ago. The Hesperian period is marked by the formation of extensive lava plains.
  • Amazonian period: Between 3.3 and 2.9 billion years ago to the present. Amazonian regions have few impact craters but are otherwise quite varied. Olympus Mons formed during this period, with lava flows elsewhere on Mars.

Mars soil is mostly alkaline containing elements such as Magnesium, Sodium, and Potassium. The Martian soil has a basic pH of 7.7.

The most significant discovery regarding the Martian surface was the presence of water channels created by running water providing the evidence that Mars was much more similar to Earth billions of years ago.

And of course, how can we forget the famous ‘Face on Mars’.

Mars is home to both the tallest mountain and the deepest and the longest valley in the solar system. Olympus Mons is 27 km high that is 3 times as tall as Earth’s Mount Everest.

Valley Marineris 10 km deep and runs for 4000 km. Scientists think that the valley was formed due to the rifting of the crust back when Mars was tectonically active.

Mars also has many volcanos, Olympus Mons being the biggest, with 600 km in diameter.

Mars also has many impact craters. The northern hemisphere is relatively smooth with few craters, whereas the southern hemisphere is heavily cratered.

The smoothness of the southern hemisphere might be because of the water that flowed across the surface many million years ago.

The largest crater on Mars is Hellas Planitia which is 1400 miles (2,300 m) wide located in the southern hemisphere.

Polar caps

Mars has two permanent ice caps in both hemispheres. The caps are in the form of dry ice in winter. The caps consist primarily of water ice (70%).

northern polar ice cap of Mars
The northern polar ice cap
NASA/JPL/Malin Space Science Systems

The south pole has a permanent dry ice cover whereas the northern hemispheres dry ice appears only during winter.

The northern poles ice cap has a diameter of about 1000 km (620 miles) and southern of about 350 km (220 miles).


Mars has two moons Phobos and Deimos, both of which were discovered by Asaph Hall.


Phobos moon of planet Mars
 Colour image of Phobos, imaged by the Mars Reconnaissance Orbiter on 23 March 2008.
NASA / JPL-Caltech

Phobos is the largest and the innermost of the two moons.

Phobos is named after the Greek god Phobos meaning Panic/fear.

Phobos orbits 6000 km (3700 miles) from the Martian surface which is closer than any other moon in the solar system.

It is so close to Mars that it completes one orbit in just 7 hours and 39 minutes. As a result, from the surface of Mars, it appears to rise from the west, move across the sky in 4 hours 15 minutes and set in the east, twice a day.

Phobos has many impact craters, the largest one being the Stickney.

Phobos is getting closer to Mars by about 2 meters every one thousand years. It is predicted to collide with the planet in the next 30-50 million years.


Deimos the smaller of the two moons orbiting 23,460 km (14,580 miles) from Mars.

Deimos moon of planet Mars
Colour-enhanced image of Deimos,

Deimos is named after Greek god Deimos meaning terror/dread.

Deimos has two named craters, Swift and Voltaire.

Unlike Phobos which rises in the west Deimos rises in the east and sets in the west.

It takes Deimos 30.4 hours to make one orbit around Mars.

Space Exploration

As we discussed earlier, Mars is the most studied planet in the solar system with over 56 spacecraft to Mars of which 26 have been successful.

Let us look at all the successful missions to Mars

Mariner 4

Mariner 4 launched in 1964 was the first spacecraft to make a successful flyby of planet Mars. It captured the first close up images of the Martian surface.

Mariner 6 & 7

Mariner 6 & 7 was the first dual mission to Mars in launched in 1969. They photographed about 20% of the planet’s surface.

Both crafts also studied the atmosphere of Mars and found out that most of the Marian atmosphere was made up of Carbon dioxide.

Mars 2 and Mars 3

Mars 2 & 3 were identical spacecraft each with an orbiter and a lander.

Mars 3s lander was the first-ever lander on Mars but contact was lost immediately and the lander was unable to send back any data.

Both orbiters sent back a total of 60 images of the planet.

Mariner 9

Mariner 9 launched in 1971 was the first spacecraft to orbit another planet.

Mariner 9 orbited Mars for 349 days capturing 7,329 photos in the process. Mariner 9 also covered 85% of the planet’s surface whereas the previous spacecraft only covered a fraction of the planetary surface.

The images revealed things like Volcanos (Olympus Mons), canyons and river beds.

Viking 1 (orbiter & lander)

Viking 1 was the first of the two Viking spacecraft sent to Mars.

It was the second spacecraft to soft-land on Mars and second to successfully complete its mission.

first colour image of planet mars by viking 1
source: NASA-JPL

The Viking lander operated on the Maran surface for 2245 sols (6 years).

Viking 2 (orbiter & lander)

Second, of the two Viking spacecraft, Viking 2 was launched in.

The lander operated on the surface for 1281 sols (1316 days).

The orbiter operated until July 1978, returning 16,000 images of the process.

Viking orbiter found river Valleys in many areas.

Mars Global Surveyor (MGS)

MGS was a global mapping mission whose goal was to map the entire planet.

In 2006, NASA released the photos of two craters captured by MGS which shows hundred of gullies formed from liquid water.

The spacecraft operated for seven years before losing contact.

Mars Pathfinder

Mars Pathfinder consisted of a lander and a rover. The rover named Sojourner was the first rover to operate on Mars.

Rover was planned to last for a week but operated successfully for 3 months.

Mars Odyssey 

Mars Odyssey was launched in April 2001 and is still active, making it the longest-serving spacecraft at Mars. Surprisingly, it has enough fuel to remain functional until 2025.

Over the years Odyssey has been the communication link between Earth and Spirit and Curiosity rovers.

Mars Express

Mars Express is the first interplanetary mission of ESA.

Mars Express is still operational making it the second longest-serving spacecraft at another planet only after Odyssey.

The spacecraft also had a lander named Beagle 2 which failed to transmit any data.

The spacecraft is expected to remain operational until 2026.


Spirit launched in June 2003 was first of the two rovers of NASA’s Mars Exploration Rover mission.

In 2009 the rover got stuck in the soft sand. NASA made many attempts to free the rover from the sand but was unsuccessful. Communication with the rover stopped on March 22, 2010 (2208 sols).


Opportunity reached Mars just three weeks after its twin Spirit.

The rover was planned to last for only 90 days but it exceeded its designed lifespan by 55 times.

With over 15 years on the Martian surface, the rover traveled a total distance of 45.16 km (28.06 miles).

Opportunity rover travel distance on 
planet Mars

Opportunity is also the rover to travel the longest off-world distance breaking the record of Lunokhod 2 (39 km).

Mars Reconnaissance Orbiter (MRO

MRO is a multipurpose spacecraft designed to conduct reconnaissance and exploration of Mars.

In 2014 MRO detected flowing salty water on Mars. The spacecraft also photographed several avalanches of the northern polar cap.

The orbiter has enough propellant to remain functional until 2030.


Phoenix was the first lander to land in the polar region of the planet. The mission lasted for over 5 months before the solar power dropped with Martian winter.


Curiosity is the biggest of the four rovers ever sent on Mars. It landed on Mars in August 2012 and is still active.

The rover’s goals include an investigation of the Martian climate and geology; assessment of whether the selected field site inside Gale has ever offered environmental conditions favorable for microbial life, including investigation of the role of water; and planetary habitability studies in preparation for human exploration.

The Mars Orbiter Mission (MOM) also Mangalyaan

Mangalyaan is the first interplanetary mission of the Indian Space Research Organisation (ISRO).

Aris Mons by Mangalyaan
Justin Cowart [CC BY 2.0 (]

Launched in 2013, it is orbiting the planet for the last five years and expected to run until 2021.

Mars Atmosphere and Volatile Evolution (MAVEN)

Mission goals include determining how the atmosphere and water, presumed to have once been substantial, were lost over time.

In 2015, MAVEN confirmed that the solar wind is responsible for stripping away the atmosphere of Mars over the years.

The ExoMars Trace Gas Orbiter 

ExoMars Trace Gas Orbiter is a joint project between the European Space Agency and Roscosmos.

The main goal of the mission is to better understand gasses like Methane, which might provide evidence for organic life.

The spacecraft also had a lander but it crashed failing to return any data.

InSight and MarCO

InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is NASA’s robotic lander designed to study the interiors of the planet.

MarCo (Mars Cube One) was a flyby mission launched alongside InSight lander. It mainly acted as a communication link between Earth and InSight during its entry, descent, and landing.

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