The planet Mars is one of the most studied Solar System objects by researchers and astronomers. It is the fourth planet from the Sun and Earth's next door neighbor.
Mars is about 4.6 billion years old and it is a rocky planet like Earth, Mercury and Venus. The planet takes 1.88 Earth years to complete its orbit around the Sun.
How Mars Was Named
Mars was named after the Roman god of war, while the Greeks called it Ares, after their own war god. History says that the Romans copied the Greeks in naming the planet after the god of war.
Steven W. Squyres, Ph.D., Professor of Astronomy at Cornell University, explains in his article The World Book at NASA how both, the Romans and the Greeks associated the planet with war because its reddish-orange color reminded them of blood.
From Earth Mars looks a bright red-orange, which is due to the iron-rich minerals in the planet's soil. Rust, composed of iron and oxygen, also has a similar color.
Observing Mars
Although Mars' reddish color makes it easy for stargazers to confuse it with red stars such as Betelgeuse or Antares, once located it is a sight worth seeing with a telescope.
The planet appears small when first viewed with a telescope, but observers will learn to find different features within the planet the more they view it. Some of the most apparent Martian features are the polar ice caps and large craters.
These will appear as different color variations within the disk; a whitish hue is noted as the ice caps grow during Mars's winter. Dark and light patches reveal craters, valleys and basins, explains Giles Sparrow, author of the book The Stargazer's Handbook.
Mars has an orbit further from the Sun than Earth does, so it circles the entire sky. This means that it moves between a position beyond the Sun, or conjunction, and opposition, when Mars and Earth line up on the same side of the Sun. During opposition Mars appears larger, since it is much closer to Earth.
These motions of Earth and Mars put the planets on opposition every 26 months. Then, because Earth moves faster than Mars around the Sun, Mars appears to loop backwards on its path for a few months; this is known as retrograde motion.
Composition of the Planet Mars
According to NASA's Mars data, It is suspected by scientists that most of the Martian crust is made of a volcanic rock known as basalt and another known as andesite. Both of these volcanic rocks are also found on Earth and the Moon.
The mantle is probably similar in its composition to Earth's, made of peridotite, a rock consisting of silicon, oxygen, iron, magnesium and the mineral olivine. The source of heat in the Martian mantle is likely to be the same as Earth's; radioactive decay, the breakup of uranium, potassium and thorium.
The Martian core is most likely composed of iron, nickel and sulfur. Mars is less dense than Earth, so it is suspected that its core is smaller than Earth's as well. Scientists also think that the core of Mars is solid and not partially molten like the Earth's because the planet has a very weak magnetic field. The motion created by a molten core is what influences the magnetic field of a planet.
The Possibility of Life on Mars
The similarities between Mars and Earth are what promote the constant question about whether life exist or has existed on Mars. Robert Burnham, one of the authors of A Guide to Backyard Astronomy, talks about a possibly Martian meteorite discovery in 1996 that was thought to contain traces of life. The conclusions drawn by scientists on this meteorite are controversial and have not been confirmed.
Squyres explains that the existence of water on Mars has raised the possibilities as well; it is believed there is water under the surface being kept liquid by the planet's internal heat. Scientists also think that liquid water once flowed in Mars because of the apparent carved channels and gullies.
Read Water on Mars Found by the Phoenix Mars Lander: Evidence of H20 on Earth's Neighboring Planet for more on the water on Mars.
Other possible signs of life on Mars are acquired from the fact that living organisms have been found in areas on Earth never before thought capable of sustaining them. The same living conditions existing in these areas are found in Mars as well. This highly facilitates the possibility of bacterial life being possible on Mars.
The Inner Solar System: A Closer Look at Mercury, Venus, Earth and Mars has more information on Mars and the Solar System.
Sources:
Burnham,R. (2002). A Guide to Backyard Astronomy. San Francisco, California: Fog City Press.
Sparrow, G. (2007). The Stargazer's Handbook. London, UK: Quercus Publishing plc
Squyres, Steven W. "Mars." World Book Online Reference Center. 2004. World Book, Inc. (http://www.worldbookonline.com/wb/Article?id=ar346000.)
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