Mars - 4th Planet from the Sun

Perhaps no planet in the Solar System is better understood, more frequently explored and travelled upon the surface by spacecraft, and more interesting to folklore and fanciful stories than planet Mars. Due to the great deal of information relative to this planet, the pages of Mars have much material that I hope you will find interesting.

Mars Quick Facts & Features

Mars is called the "Red Planet" due to the rust-colored rocks and sand grains that dominate the surface. It is so red that the ancients often associated Mars with war and named it after their gods of war.

Mars is roughly one half the size of the Earth with similar lengths of a day and somewhat reasonable temperatures ... if you like winter on Earth.

The major features that distinguish Mars include its truly grand canyon (The Valles Marineris), lofty dormant volcanic mountains (Olympus Mons is the biggest in the Solar System), and polar icecaps of carbon dioxide and water ice.


Mars has two moons (Phobos and Deimos) that are tiny compared to Earth's moon.

Percival Lowell is the astronomer credited with the greatest study of Mars, but his observations were flawed and caused a tremendous stir among the general population in the early 20th century.

At one time in the very distant past (some estimates claim 4 billion years ago), Mars had a large amount of water creating oceans, lakes, and rivers. It is the theory of many that when the magnetic field of Mars shut down, there was no longer any protection from the solar wind, and thus the atmosphere and water supplies were blown off of the surface of Mars and out into deep space.

Mars is presently occupied by two roving robitic spacecraft (Spirit and Opportunity) that continue to provide detailed information about the surface of Mars.

Planetary Data

Mass (kg), and mass relative to Earth

6.419x10^23 kg = .1074 earths

Equatorial diameter (km)


Mean density (gm/cm^3)


Acceleration of gravity (m/s^2)


Velocity of escape (km/s)


Period of rotation

24.6229 hours

Period of revolution

1.8809 years

Aphelion (AU)


Aphelion (km)


Perihelion (AU)


Perihelion (km)


Mean orbital distance from the sun (AU)


Mean orbital distance from the sun (km)


Orbital velocity (km/s)






Inclination to the ecliptic

1.850 degrees

Inclination of the equator to the orbit

25.19 degrees

Number of natural satellites


Names of natural satellites

Phobos, Deimos


Please link to the Mars Page to enter into a more detailed study of this fascinating planet.

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