ESCI 110: Planetary Surfaces Page 3-1 Introduction Exercise 3 Surfaces of the Planets and Moons Our knowledge of the solar system has exploded with the space exploration programs of the last 40 years. This new knowledge has led to two major conclusions: 1) impacts of objects crashing into planetary and lunar surfaces was very important in modifying these surfaces, especially early in the history of the solar system, and 2) the earth is unique within the solar system compared to the other planets and moons. In this exercise we will look at planetary surfaces and introduce the general categories of materials they are made of and the processes that modify them. Objectives Upon completion of this exercise, you should be able to: List the types of materials that make up planetary surfaces Provide examples of planets or moons with surfaces dominated by gasses, ice, rocks or liquid water List the basic types of processes that modify planetary surfaces Identify the effects of different processes in modifying planetary surfaces Determine the relative age of different surfaces on the same moon or planet Background Information In a very general way, the composition of the surfaces of the moons and planets can be divided into four major categories: Gas giants. The Jovian planets apparently have no solid surface as we would be familiar with it. Instead, they are composed of giant balls of gas, with the gasses becoming denser with depth until they gradually turn into liquid. The outer surfaces of these planets are therefore in constant motion. Ice surfaces. These surfaces are dominated by frozen liquids that have relatively low melting points. Any process that generates enough heat will therefore melt the surface, smoothing it out. Rocky surfaces. These surfaces are dominated by solid materials that have relatively high melting points, and are capable of maintaining substantial relief over time. Liquid surfaces. Significant portions of the planet are covered with liquid. The processes which modify planetary surfaces can be divided into the following categories:
ESCI 110: Planetary Surfaces Page 3-2 Impacts. Objects that strike the surface of a moon or planet are typically traveling at tens of thousands of kilometers an hour relative to the target. On a solid surface the collision will leave an impact crater. A relatively fresh impact crater may send rays of ejecta across the land, and large craters will generally have a raised area in the center caused by the rebound of rocks compressed directly under the impact site. Volcanoes. Volcanoes are mountainous landforms that build up where liquid rock material escapes from the surface of the planet or moon. In many cases lava flows may be found extending from the central vent of the volcano. Tectonics. Forces within the moon or planet may put stress on the surface, and modify it in the form of faults or folds. Surface processes. If the moon or planet has an ocean or atmosphere, the surface may be significantly modified by the influence of wind, running water, ice, waves or gravity. One very important consideration in studying the history of a planetary surface is to determine the age of the surface under study. Impacts occurred at the greatest rate early in the history of the solar system, and impact craters also accumulate over time. Therefore older surfaces will have a higher density of impact craters than younger surfaces. We can also use the principle of crosscutting relationships to determine the relative age of adjacent surfaces. If a fault cuts through an impact crater, for example, we know that the crater had to be there before the fault began to move. Pre lab Exercise Use the words below correctly in a sentence Lunar Highlands Maria Meteorite Answer question 5, from 650.
ESCI 110: Planetary Surfaces Page 3-3 Lab Exercises Questions (If any of the images are unclear ask your instructor to display them up on the screen so you may observe a clear photograph) 1. The image to the right shows part of the surface of the moon. The lighter area on the left is part of the lunar highlands, while the dark region on the right is part of one of the maria. Which process from the list above dominates the surface of the highlands? Which surface is older, the highlands or the maria, and how can you tell from this photo? 2. The image to the right shows part of the surface of Mercury. Is this surface gaseous, icy, rocky or liquid? From what you see in the image, is the surface of Mercury closer in age to the highlands of the Moon or the lunar maria? Explain the reason for your answer. 3. This image shows part of the surface of Jupiter. What type of material is Jupiter made of, and what is your evidence? Jupiter was recently struck by several pieces of a large comet. Circle the evidence of impact you see on this image, and describe what has happened to these impact structures since they formed:
ESCI 110: Planetary Surfaces Page 3-4 4. The image to the right is a radar image that shows the solid surface of part of Venus beneath the clouds. The surface of Venus is clearly composed of rocky material and volcanoes that are at least somewhat similar to that found on parts of the earth. What process is responsible for this part of the landscape on Venus? How old is the surface of this part of Venus compared to the surface of the Moon?
ESCI 110: Planetary Surfaces Page 3-5 Jupiter s moon Io Surface of Ganymede Close up of Surface of Ganymede Surface of Europa 5. These four images show surfaces of three of the moons of Jupiter. What type of material is the surface of Europa composed of? What process dominates the surface of Io? _ What evidence do you see for tectonic activity on Ganymede? Which part of which moon appears to be the oldest in age, and what evidence supports that conclusion from the images provided?
ESCI 110: Planetary Surfaces Page 3-6 Olympus Mons Dune Field Ophir Chasma 6. The three images above show different parts of the surface of Mars at three completely different scales (Olympus Mons is the size of Ohio, Ophir Chasma is as deep as the Grand Canyon, and the dune field is show at a high magnification). Overall, is the surface of Mars relatively young or very old? Which two processes dominated the surfaces in these regions? 7. Earth. This photo has been converted to a grayscale image from a color photo taken by the Apollo 17 astronauts. Saudi Arabia is in the middle of the picture. What two types of materials dominate the visible surface of the earth? What evidence do you see for tectonic activity in this image? Is the surface of the earth relatively young or relatively old compared to other planetary surfaces, and how can you tell?