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Regions, Valles Marineris, Channels
INTRO:
One of the most compelling arguments in the theory of life on Mars is
the similar conditions on Mars and Earth. While these conditions are
not VERY similar, the conditions on Mars are more similar to Earth
than any other planet. Fortunately or unfortinuately, we still would
not survive on Mars. While Earth's surface temperature ranges from -126.8
degrees Fahrenheit to 136 degrees Fahrenheit, Mars' temperature rarely
rises above 32 degrees Fahrenheit. There is no visible water running on
its surface, but scientists believe it may have existed millions of years
ago and now exists frozen under the polar caps or surface. Mars' surface
is characterized by three distinctive regions- bright areas, dark areas,
and polar caps.
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REGIONS:
The bright areas
cover about two-thirds of Mars' surface. They resemble the
southwestern
deserts of Earth in terms of conditions and
color. They contain limonite, a reddish rust-brown mineral, that give
Mars its red color. They are very dry, resembling our deserts with dust,
sand, and rocks.
Covering one-third of Mars' surface,
the dark area, called maria (the Latin word for seas), changes colors depending
on the season Mars. During the Martian fall and winter, the
maria may turn so light that they disappear. During
the spring and summer, it becomes dark. Typically, the dark areas look
greenish-gray or bluish gray. Astronomers believe these color changes are because of
the wind. They believe that the wind will blown sand around, covering
and uncovering parts of Mars' surface.
The polar caps on
Mars take up a small area near its north and south poles. From Earth, these
caps look white, leading scientists to believe there may be large
quantities of water frozen there. Like the maria, the polar caps change
with the seasons. During the spring and summer, when Mars is tilted towards
the sun, the polar caps evaporate and shrink. During the fall
and winter, they freeze again and grow larger. The evaporation during the
summer and spring may actually be providing water vapor in Mars' atmosphere. The southern
polar cap especially interest scientists because of its slightly red tint. The southern
polar cap is actually frozen carbon monoxide. The red tint is the
result of dust getting frozen inside the carbon monoxide.
Besides the three
regions, Mars also has numerous craters from the impact of past
meteorites. For example, the Hellas Basin is a HUGE Texas-sized crater
that has been eroded through years of erosion. Scientists use
erosion to help estimate the ages of the craters on Mars. The
surface also has canyons, gorges and features that resemble dry riverbeds.
This provides further support
to the belief that Mars once had water flowing on it. Volcanos
are also present on Mars, mainly on or near the
equator. These volcanos are much larger the largest volcano on Hawaii.
In fact, the largest volcano on Mars, calle Olympus Mons, is twice the
size of Mount Everest, the tallest mountain on Earth. Olympus Mons is
the largest known volcano in the whole solar system. If laid down, it would
stretch from Chicago, Illinois to St. Louis, Missouri!
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VALLES
MARINERIS:
Valles Marineris is the largest canyon in the solar
system. It is 124 miles wide and four times as deep as the
Grand Canyon. It would stretch across the WHOLE UNITED STATES!
So long that one end of the canyon is still in nighttime, while the other
end is in daytime! So big, it covers one third of
Mars' surface!
To compare Valles Marineris to the Grand
Canyon would be wrong. Valles Marineris actually has more in common
with the Red Sea, Gulf of California, and the Great Rift Valley of Africa
than it does with the Grand Canyon. Sometimes, Valles Marineris is
called the cousin of the Red Sea. They are related in the way they
were formed. Unlike the Grand Canyon, which formed when the Colorado
River cut through it, the Valles Marineris formed when the crust of Mars
began to pull apart. This is similar to the Red Sea and the Great
Rift Valley of Africa. Many "marsquakes" resulted in the land being
split apart as the material moved around. Scientists say it
resembles an early, almost prehistoric, Atlantic Ocean as Europe and the
United States began to drift apart.
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CHANNELS:
In 1877, Giovanni V. Schiaparelli noticed many
lines criss-crossing Mars' dark area. He called these lines "channels",
but when it was translated from Italian to English, it became "canal".
This lead to the misconception that Mars actually had canals running
through its maria. Many people took that to mean Mars was inhabited.
These channels may provide evidence that water flowed on Mars at one point. They travel downhill, join at tributaries, and empty into plains, sometimes with a delta at their mouths. (All these are characteristics of rivers.) Still, these channels can easily be explained. They are NOT the results of Martians. They could have formed through geothermal heating or groundswater sapping. Geothermal heating is when floods of water gush up and erode the soil into channels. Groundswater sapping, like in arid areas of Earth, is when underground permafrost becomes exposed. They begin to melt, or sometimes even sublime. The soil caves in and channels form.
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