WELCOME TO MARS!
Mars is the fourth planet from the Sun in the Solar
System. It is the next one beyond Earth's orbit. Its red
color inspired the Greeks and the Romans to name it after
their god of war, Ares or Mars. At times it is the third-
brightest object in the night sky. Mars is half the size of
Earth but nearly twice the size of the moon.
The Martian orbit is very elliptical. The planet's distance
from the sun varies from a minimum of 128.4 million miles to
a maximum of 154.8 million miles. Mars speeds along at 15 mi/sec
counterclowise as all the other planets.
The Martian day is 24 hours, 37 minutes, and 23 seconds long.
Due to the tilt of the planet's axis, seasonal changes are similiar
of Earth's. No measurable magnetic field for Mars has been detected,
which indicates that the core is solid and explains why Mars has no
radiation belt. The total mass of the planet is only one-tenth that
of Earth, and thus Martian gravity is only 38% as strong.
Mars has two moons, Phobos and Deimos. Each is only a few kilometers
wide. The moons are heavily cratered and may be asteroids captured by
Mars. The Martian atmosphere contains mainly carbon dioxide (95.3%),
nitrogen (2.7%), and argon (1.6%). The Martian atmosphere undergoes
dramatic daily and seasonal temperature changes. It averages about
-64 degrees Fahrenheit. Mars and Earth has similarities such as
atmospheric circulation and seasonal climate changes.Surface Features:
The
Martian surface has weathered basaltic rock and iron oxides. Most of the suface is covered
by thin deposits of dust and sand that are easily transported by winds.
The presence of windblown deposits, pebbles, and cobbles has been
confimed by U.S. VIKING landers.
Mars has no oceans. Elevations on the planet are average surface level.
The canyon system of Valles Marineris, the largest and deepest known
in the solar system, is located on Mars.
Geological Evolution:
Although the overall geologic character of Mars is unique in the solar
system, it shares characteristics of both the Moon and Earth. This
comes as no surprise, because Mars is similiar in composition to both
bodies. The size of Mars can be explained by the lack of platetectonics
on Mars, and by the planet's less erosive atmosphere and climate. Another
major difference between the two planets is the catastrophic flooding that
has occured on Mars when its abundant ground water was released in great
volumes.
Past and Future Studies of Mars:
It was due to Mars very elliptical orbit that Johannes Kepler determined
in 1609 that the planets revolve in an elliptical orbit. This abolished
the older Ptolemaic theories. The very next year, Galileo made the first
telescopic observation of the planet and recorded its phases. In the late
1600s other scientists made closer observations of Mars, determining that
its rotation period is close to Earth's, that it has polar caps that show
seasonal change , and that dark areas could be distinguished . These were
thought to be seas. In the late 1700s William Herschel noted bright, changing
patches patches that he thought were clouds, suggesting that the planet had
an atmosphere. He and later astronomers therefore shared the view that life
thrives on Mars.
Knowledge of the planet has greatly increased through spacecraft missions,
such as Mariner 4, Mariner 6 and 7, Mariner 9, and Viking Orbiters and landers.
Their biological experiments found no evidence of organic material. Hospitable
conditions for life may be present, however, in warm, wet subterranean enviroments
(if such exists). Other scientists think that life may have existed early in Mars"s
history, when climate conditions were probably more favorable. Spacecraft missions
will continue to be the most productive source of new data for Mars. Various spacecraft
missions are in the planning stage. They include landers capable of sophisticated on-site
measurements, sample return, seismic detection, and roving , robotic investigation. Such
studies are expected to provide further insight into the planet's composition , structure,
atmosphere, and possible biology, as well as to open the door for human exploration of the
planet.
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Thank you for visiting the RED PLANET! |
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This page was written by Richard Ledgister in the Astronomy Class of BCC/Broward County July 1998 |