You will be asked to answer this question during Exam 2 on Thursday, November 10. Please think about how you will answer this question before the exam, and write your answer during the exam time.

Name: _________________________        Section Number:________

Throughout this part of the course, we have looked at the planets of our Solar System, and the small bodies that attend them. Though they display a huge range of properties, there are some important similarities between features found on their surfaces, and in their atmospheres.

With this in mind, answer part A, and then choose either part B -or- part C to finish your essay. Do not answer both B and C - we will grade only one of them.

1. (15 pts) Briefly explain why size is the most important factor influencing the surface appearance of the terrestrial planets (and large satellites). In your answer, be sure to
   1. State what the influence of size is on all four basic geological processes we discussed in class.

   2. Give an example of two objects in our solar system that are approximately the same size but, surprisingly, have different surfaces and explain why the two objects have different surfaces.
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2. (5 pts) In all planets that have atmospheres, we see clouds. For example, the clouds of Venus appear greenish-white; Earth clouds are white, Jupiter has white, brown, and even red clouds, Neptune has a vivid blue-green color. Pick a pair of planets with very different cloud features and explain why the clouds look different on each planet. For each planet be sure to mention the main constituent of its atmosphere and that of the clouds we see.

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3. (5 pts) Impacts of bodies larger than 100m in diameter produce craters on the surfaces that they hit. We see a large number of craters on the surfaces of most satellites of the planets, and on most planets, yet we see few on the surface of the Earth. Why don't we see lots of craters on the land surfaces of Earth?