Comparative_Planetology_Online_Lab_v2

Online Lab: Comparative Planetology Name: Date: Instructor: Section: Introduction The goal of this lab is to explore the solar system using a series of images taken by many different spacecraft. One of the most important areas of astronomy is the field of comparative planetology. By studying planets and other large bodies in the solar system, we learn about the history and possible future of our own. Some large bodies, such as Mars, Mercury and the Moon, have preserved a record of the history of the solar system, in their craters and in the evidence for lava flows and other surface alterations. On the other hand, Venus gives a frightening glimpse into a possible future of the Earth, should the “greenhouse effect“ become significant here. Even the giant planets, different though they seem, offer insight into the formation of the solar system, its stability, and its history, and therefore are important to a complete understanding of the Earth’s history. In particular, the moons of the outer planets are in some cases comparable to inner solar system objects. Part A: Craters Around the Solar System Use the images below (Figures 1 - 6) to answer the following questions. Figure 1: Meteor Crater in Arizona Figure 2: Mercury: Optical Image From Mariner 10 Written by University of Washington, Modified by Melissa Butner 1

Figure 3: Venus: Crater Cunitz Figure 4: Footprint on the Moon Figure 5: Mars: Optical Image 1 Figure 6: Lunar Craters Written by University of Washington, Modified by Melissa Butner 2

Part B: Volcanism Around the Solar System Volcanism can be very important in shaping the surface features of a planet. Venus has a large number of unique volcanic features. On Earth, when volcanos erupt, the molten lava within them can travel great distances before it cools. However, on Venus, molten lava does not travel very far before it cools. Compare these examples of shield volcanoes on Venus and on Earth. Figure 7: Shield volcanoes on Venus - Pancake Domes Figure 8: Shield volcanoes on Earth - Galapagos Islands 1. Give two pieces of evidence that Venusian lava does not flow far before cooling. 2. What might cause the difference between the two planets? Written by University of Washington, Modified by Melissa Butner 4

Part C: Channels of Mars Life as we know it requires water. Because of this, observations implying the possibility of water on Mars are of tremendous interest for scientists and the general public. Compare these pictures of Earth and Mars. Figure 9: Mars Channel Features Figure 10: Imprint of flowing water in the desert of the Republic of South Yemen 1. What are the similarities between these surface features? What does this suggest about the possibility of water on Mars? 2. Scientists who disagree with the hypothesis that the Martian channels were caused by flowing water often point out that it is not clear where the water comes from, or where it goes. In the Yemen image, the water flows from the top of the image in a number of tributaries which combine to form the river which flows off the bottom of the image. This implies that “down“ in the image is downhill on Earth. Examine the Mars Channels. Which direction is downhill? How do you know? Written by University of Washington, Modified by Melissa Butner 5

1. The different compositions of the outer planets give them their different colors. Jupiter and Saturn appear yellowish and reddish because of the polysulfides and phosphorus in their atmospheres. Uranus and Neptune have more methane and ammonia in their atmospheres and so they appear bluish. Notice that while Jupiter, Saturn and Neptune have much structure in their atmospheres, Uranus looks very smooth with no obvious features. What does this tell us about the interior of Uranus compared to the other giant planets? 2. The bands and stripes on Jupiter, Saturn and Neptune are common to all planets with atmospheres. On the Earth, these bands are trade winds (westward surface winds), and jet streams (eastward high-altitude winds). On the Earth, and Venus, the energy that drives the winds comes from the Sun, which heats the ground and the lower atmosphere, starting the process of convection. However, Jupiter, Saturn and Uranus have no “ground“, and are much too far from the Sun for their winds to be “solar-powered“. Where does the energy to drive these winds come from? Written by University of Washington, Modified by Melissa Butner 7

Part E: Physical Data of Solar System Bodies Use the data given in Table 1 to answer the next four questions. 1. How do the Sizes , Masses and Densities of the terrestrial planets compare to those of the gas giants? 2. What does the physical data tell us about the composition of the planets? Explain. 3. Based on the physical data, does Pluto most resemble a terrestrial or a gas giant? Why? 4. Do the minor bodies, Ceres and Halley fit into either group based on the physical data? If so, which? Why? Written by University of Washington, Modified by Melissa Butner 8

Table 1: Physical Data of Solar System Bodies Type Object Radius Mass Density Rings Atmosphere Star Sun 690,000 2.00E+30 1410 No All Gas Terrestrial Planets Mercury 2,440 3.00E+23 5430 No No Venus 6,052 5.00E+24 5240 No Thick Earth 6,378 6.00E+24 5520 No Thick Mars 3,394 6.00E+23 3930 No Thin Gas Giants Jupiter 71,492 2.00E+27 1330 Yes All Gas Saturn 60,268 6.00E+26 690 Yes All Gas Uranus 25,559 9.00E+25 1270 Yes All Gas Neptune 24,766 1.00E+26 1690 Yes All Gas Dwarf Planet Pluto 1,137 1.00E+22 2060 No Variable Asteroid Ceres 480 9.00E+20 2700 No No Comet Halley 16 1.00E+14 170 No Variable Table 2: Orbital Data of Solar System Bodies Type Object Semi-Major Period Eccentricity Inclination Axis (AU) (yr) ( ◦ ) Star Sun Terrestrial Planets Mercury 0.39 0.24 0.206 7.00 Venus 0.72 0.62 0.007 3.39 Earth 1.00 1.00 0.017 0.01 Mars 1.52 1.88 0.093 1.85 Gas Giants Jupiter 5.20 11.86 0.048 1.31 Saturn 9.54 29.46 0.056 2.49 Uranus 19.18 84.01 0.047 0.77 Neptune 30.06 164.80 0.009 1.77 Dwarf Planet Pluto 39.44 248.60 0.249 17.20 Asteroid Ceres 2.77 4.60 0.079 10.58 Comet Halley 17.80 76.60 0.967 52.04 Written by University of Washington, Modified by Melissa Butner 10