Planetary Systems Essay

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Week 3 Discussion Questions 1. Mars: What is the evidence that water once flowed on Mars? -Why do some scientists think Mars once had an extensive ocean? Where was it located? By exploring the surface of mars astronomers have found evidence of runoff channels and outflow channels from what they believe to be running water a long time ago. It is the outflow channels that suggest that very large volumes of water once flowed into a large body or ocean of water (Chaisson & McMillan, 2011). Looking at the surface of mars astronomers is able to see evidence of terrace beaches that could be the remains of shoreline from a large body of water. In 2003 the Mars Global surveyor data indicated that the surface of mars does not contain enough carbonate rock layers to suggest that ancient oceans once covered the planet (Chaisson & McMillan, 2011). However, there is evidence of hydrated chemical compounds on the surface rocks of mars which would be evidence to support the theory that large areas were wet for a long duration of time (Chaisson & McMillan, 2011). -What is the evidence that Mars never melted as extensively as did Earth? By looking closely at impact craters there is indications that suggest that there may be water below the surface of mars. It is the ejecta blanket around the craters that tell geologists that permafrost (water ice) lies just beneath the surface of the planet (Chaisson & McMillan, 2011). Due to mars distance from the sun in contrast to earth there is no way that mars could experience the level of ice melting that has been seen on earth. 2. Venus + Mars: Compare and contrast the evolution of the atmospheres of Mars, Venus, and Earth. Scientists speculate that earth and Venus may have had very similar atmospheres at one time. 4 Billion Years ago the gasses surrounding earth were released by all the volcanic activity

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