Mars is the fourth planet from the Sun, and is located between Earth and Jupiter.
It is named after the Roman god of war, because of its reddish color in the night sky.
The planet is smaller than Earth and colder since it is further from the Sun and has a very thin atmosphere.
Mars rotates around the Sun following an eccentric orbit.
Since Mars is twice the distance from the Sun as the Earth, the Martian year is twice as long.
However the Martian day has approximately same duration as Earth's due to its similar axial rotation.
Mars is the most Earth-like planet in the Solar system.
A few billion years ago water even flowed on its surface!
Imagine a frozen Earth desert with reddish sands and a pink sky. The surface looks reddish because high amounts of iron.
The landscape has all sorts of landforms similar to Earth: valleys, plains, mountains and large volcanoes.
The highest mountain in the Solar System is located on Mars. The mountain, Olympus Mons
is of volcanic origin and raises 86,600 feet above the average surface level, about three times higher than Mount Everest!
While some areas are heavily covered with craters, formed by asteroids
smashing into its surface, others are smoothed by lava flows.
The cracks and canyons are probably the result of past "marsquakes".
There are also huge valleys, like Valles Marineris
, many times larger than the Grand Canyon
Scientists were excited to find what appear to be large river channels, formed by ancient water flows.
What happened to the water? This question is still quite puzzling.
It may have escaped into the space or still lies frozen in the soil in a form of "permafrost."
Mars also has ice caps at its North and South poles.
Mars has a thin atmosphere that consists mainly of 95% carbon dioxide
, water vapor and argon
This Martian atmosphere
is about 100 times less dense than the atmosphere surrounding Earth.
The atmospheric pressure
on the surface is less than one percent of the Earth's at sea level.
The average temperature ranges from -55 C to -67 C
, however it varies according to the seasons.
During the summer, when the polar caps melt, the solid carbon dioxide or dry ice turns into gas and
substantially raises the atmospheric pressure by 25 percent increasing the surface temperature.
is very interested in learning more about the possibility of life on Mars,
and so has been developing a series of spacecraft to orbit and land on the surface.
Eventually, the plan is for people to visit!
NASA first sent the Viking
spacecraft to orbit and land on Mars back in the 1970's.
Launched in 2001, NASA's Odyssey
spacecraft is still in orbit around Mars and has collected over 130,000 images.
Odyssey also determined that radiation in low orbit is twice the radiation in low earth orbit.
Radar measurements of the South pole, made by Mars Express
(an international collaboration launched in 2003),
show that there is enough ice to cover the planet with water 11 meters deep if the ice melts.
In 2005, NASA's Mars Reconnaissance Orbiter
was launched carrying the most powerful camera ever to be used in such a mission.
In fact, the camera is so powerful that it can zoom in on surface objects as small as footballs.
The latest data from these missions proved that liquid water did flow on Mars and may still exist there.
The abundant amount of water, probably gradually froze when tectonic and volcanic activity on Mars stopped a few millions years ago.
Exploration Continues: The Next Mission to Mars
Due to the success of Spirit and Opportunity, two robotic geologists or land rovers that landed on the Martian surface in 2004,
NASA's next international collaborative rover mission to Mars is scheduled for 2012.
This new larger rover with enhanced instruments for gathering more scientific data is called
the Mars Science Laboratory
It will be able to collect samples of rock and debris from the surface and analyze the samples on board,
hence the name Mars Science Laboratory.
Mars also has two tiny moons, named Phobos
after Greek gods of fear and panic.
These moons are small and lumpy, and look like asteroids. Scientists think that they were probably captured by Mars from an asteroid belt.
Phobos has a diameter of about 22 km and orbits above the Martian surface at about 6000 km.
Phobos is the closest moon to its planet in the entire Solar System.
Because it is so close it rises and sets twice a day from west to east.
The smaller and outermost moon, Deimos, has an average diameter of 12.6 km and orbits about 23.5 km from Mars.
One of the most famous features on Mars is Cydonia
, known as 'The Face on Mars'.
It was first photographed by Viking's Orbiter 1
in 1976 when searching for suitable lending sites.
The low resolution images of this hill region resembled a human face and were basis for many speculations that the hills were artificially made.
However, recent more detailed images of Cydonia, transmitted by spacecraft with higher resolution cameras
prove that "the face" is a result of shading, low resolution photos, high landforms called mesas, and human imagination.