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TO GO TO ANY OF THE PAGES LISTED BELOW, CLICK ON ITS TITLE CHAPTER 17 The Solar System 1 17-1 What is the solar system? 2 17-2 What do we know about orbits? 3 Comparing Planetary Revolutions Enrichment Activity for Lessons 17-1 and 17-2 4 THE BIG IDEA Integrating Physical Science: What keeps the planets and moons in orbit? 5 17-3 What do we know about Earth s Moon? 6 17-4 What are the other moons in the solar system? 7 17-5 What do we know about Mercury, Venus, and Earth? 8 Earth Statistics Enrichment Activity for Lesson 17-5 9 17-6 What do we know about Mars? 10 17-7 What are asteroids and meteoroids? 11 17-8 What do we know about Jupiter and Saturn? 12 17-9 What do we know about Uranus, Neptune, and Pluto? 13 Naming Moons and Planets Enrichment Activity for Lessons 17-6, 17-8, and 17-9 14 Comparing the Planets Enrichment Activity for Lessons 17-6, 17-8, and 17-9 15 17-10 What is a comet? 16 Chapter 17 Key Term Review 17 Chapter 17 Test 18 Chapter 17 Answer Key 21 (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 1

17-1 What is the solar system? Complete the following. 1. What is at the center of our solar system? 2. How many planets are in our solar system? _ 3. Name the inner planets. 4. Name the outer planets. 5. What is an orbit? 6. Describe the theory that explains how the solar system was formed. Skills: sequencing, modeling, identifying In the spaces provided, label the orbit of each planet as shown in the diagram. 1. 2. 3. 4. 6. 7. 8. 9. 5. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 2

17-2 What do we know about orbits? PART A Complete the following. 1. What is the difference between a circle and an ellipse? 2. What is the shape of a planet s orbit? 3. What is orbital velocity? 4. What is the relationship between the gravitational attraction between two objects and their distance from each other? PART B Decide whether each statement describes Earth s aphelion or perihelion. Place a check mark in the correct column. Statement Aphelion Perihelion 1. 147,000,000 2. Occurs in July 3. Earth slowest in its orbit 4. 152,000,000 5. Earth fastest in its orbit 6. Occurs in January Skills: interpreting a diagram, applying concepts Study this solar system. Then, answer the questions. 1. How many planets make up this solar system? 2. What is the shape of the planets orbits? 3. Which planet has the greatest orbital velocity? 4. At which point will Planet D move slowest in its orbit E or F? 5. Which planet has the slowest orbital velocity? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 3

Comparing Planetary Revolutions Enrichment Activity for Lessons 17-1 and 17-2 Skills: researching, analyzing, comparing PART A The amount of time it takes a planet to complete one trip around the Sun is called a revolution. Use reference materials to find about how long it takes each planet to complete one revolution. PERIODS OF REVOLUTION Planet Period of Revolution (in Earth time) Mercury 1. Venus 2. Earth 3. Mars 4. Jupiter 5. Saturn 6. Uranus 7. Neptune 8. Pluto 9. PART B The amount of time it takes a planet to revolve around the Sun is known as a year on that planet. The planets all have years of different lengths. Use the information from the table above to answer the following questions. 1. Which planet has the shortest year? 2. Which planet has the longest year? 3. What is the relationship between the distance of a planet from the Sun and the length of its year? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 4

THE Big IDEA Integrating Physical Science Chapter 17 What keeps the planets and moons in orbit? Refer to the article, call outs, and illustrations on pages 412 and 413 of your text to answer the following questions. 1. When you throw a ball, what causes it to follow a curved path? 2. How is the motion of the planets around the Sun similar to the motion of a ball that is tied to a string? 3. a. What is gravity? b. How does gravity keep the planets from spinning off into space? Skills: inferring, analyzing, estimating Complete the following. 1. What relationship exists between a planet's distance from the Sun and its period of revolution? 2. Approximately how old would you have to be to witness one complete revolution of the planet Pluto? Science Log Writing Activity Complete the Science Log on a separate sheet of paper. To complete the Big Idea Online, go to www.conceptsandchallenges.com. Follow the online instructions. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 5

17-3 What do we know about Earth s Moon? Complete the following. 1. The first American astronauts set foot on the Moon s surface in the year. 2. The last spaceship to carry astronauts to the Moon was. 3. Earth has moon. 4. Gravity on the Moon is only as strong as gravity on Earth. 5. The Moon has no liquid water and no. 6. The three main types of features on the Moon s surface are,, and. 7. Most craters on the Moon were caused by. 8. Some craters may have been caused by. 9. Astronauts need to wear to survive on the Moon. Skills: applying concepts, calculating Complete the following. 1. If an object on Earth weighs 6 pounds, how much will the object weigh on the Moon? 2. If an object weighs 10 pounds on the Moon, what will the object weigh on Earth? 3. You can jump six times higher on the Moon than you can on Earth. If you can jump 1.5 meters on Earth, how high can you jump on the Moon? 4. If you can jump 6 meters on the Moon, how high can you jump on Earth? 5. If you can kick a football 20 meters on Earth, how far can you kick the football on the Moon? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 6

17-4 What are the other moons in the solar system? Complete the following. 1. What is a satellite? 2. Which planet has the most known moons? 3. Which two planets have no known moons? 4. What is the name of Saturn s largest moon? _ 5. Which two planets have only one moon? 6. Which planet s four large moons were discovered by Galileo? Skills: analyzing, organizing data, researching Complete the table. Planet Name CHARACTERISTICS OF PLANETS Number of Names of Some Moons Moons 1. 1 2. Saturn 3. 4. Mars 5. Phobos, Deimos Mercury 6. 7. 8. 8 Triton, Nereid Pluto 9. Charon 10. 21 11. 12. 28 13. 14. 15. no moons (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 7

17-5 What do we know about Mercury, Venus, and Earth? Complete the following. 1. Which planet travels fastest around the Sun? 2. What is the temperature range on Mercury? _ 3. What gas makes up much of the atmosphere of Venus? _ 4. What makes Venus a hostile world? 5. What is unusual about the rotation of Venus? 6. Describe the surface of Venus. 7. What makes life on Earth possible? 8. What causes Earth s magnetic field? Skills: organizing, comparing Complete the table. Planet MERCURY, VENUS, AND EARTH Position Relative Surface Features to the Sun Mercury 1. 2. Venus 3. 4. Earth 5. 6. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 8

Earth Statistics Enrichment Activity for Lesson 17-5 Skills: researching, modeling PART A Answer the following questions about Earth. Use reference materials to help you. 1. How old is Earth? 2. How long does it take Earth to rotate, or spin around once, on its axis? 3. How long does it take for Earth to circle the Sun once? 4. How far is Earth from the Sun? Give your answer in astronomical units. 5. What is the exact diameter of Earth? Give your answer in kilometers. 6. What is the mean surface temperature on Earth? Give your answer in Kelvins. 7. What is the highest land feature on Earth? 8. What is the lowest place on Earth s surface? PART B About 30 percent of Earth is land, and 70 percent is water. On the diagram of Earth, shade in the number of bars to show the relationship between the amount of water and land. Use different colors for water and land. Include a key for your diagram. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 9

17-6 What do we know about Mars? Complete the following. 1. What gas makes up most of the atmosphere of Mars? 2. What do scientists think are the reasons that there is no liquid water on Mars now? 3. What is Mars s orbital period? 4. Why does Mars have seasons similar to those on Earth? _ 5. Describe the surface of Mars. 6. What is the name of the large volcano on Mars? 7. What is Vallis Marineris? Skills: comparing, classifying Decide whether each feature belongs to Earth or Mars or both. Place a check mark in the correct column. 1. Polar ice caps 2. 687-day orbit period 3. 24-hour day 4. Liquid water 5. Volcanoes 6. Seasons Feature Earth Mars Both 7. Dust storms that cover the entire planet 8. Largest known volcano in the solar system 9. Reddish surface 10. Thin atmosphere of carbon dioxide (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 10

17-7 What are asteroids and meteoroids? Complete the following. 1. A large chunk of rock that orbits the Sun is _. 2. A piece of rock or metal that strikes Earth s surface is a. 3. A piece of rock or metal that enters Earth s atmosphere is a. 4. Most asteroids are located between. 5. Asteroids are made up of. 6. Large meteoroids may have been formed by collisions between. 7. A meteorite may leave a large when it strikes Earth. 8. The first asteroid to be discovered was. Skills: diagramming, modeling Most asteroids orbit the Sun in the Asteroid Belt, which lies between the orbits of Mars and Jupiter. Other groups of asteroids have different orbits. Some asteroids called Trojans follow the same orbit as Jupiter. Other groups of asteroids, called near-earth asteroids, orbit in the inner solar system. The orbits of some near-earth asteroids cross the orbits of Earth and Mars. On the diagram below, draw the three different orbits of the asteroids. Label the Asteroid Belt, the Trojan asteroids, and the near-earth asteroids. Use your text and reference materials to help you. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 11

17-8 What do we know about Jupiter and Saturn? PART A Decide whether each statement describes Jupiter or Saturn. In the space provided, write J for Jupiter or S for Saturn. 1. is the largest planet in the solar system 2. is the second largest planet in the solar system 3. was hit by comet Shoemaker-Levy 4. has Great Red Spot as a feature 5. has a diameter of 121,000 6. has a density that is only one-fourth the density of Earth 7. has a diameter of 143,000 8. is less dense than water PART B Place a check mark beside each statement that applies to both Jupiter and Saturn. 1. is a gas giant 5. is more dense than Earth 2. has a Great Red Spot 6. is less dense than Earth 3. is surrounded by colored bands of clouds 7. can be seen easily without a telescope 4. is larger than Earth 8. is made up mostly of hydrogen and helium Skills: applying concepts, labeling In the space provided, identify whether each circle represents Earth, Saturn, or Jupiter. Then, label the distance of the diameter of each planet. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 12

17-9 What do we know about Uranus, Neptune, and Pluto? Write true if the statement is true. If the statement is false, change the underlined term to make the statement true. 1. Uranus is the eighth planet from the Sun. 2. The atmosphere of Uranus contains methane, as well as hydrogen and helium. 3. Neptune is similar to Uranus in size and mass. 4. Pluto has a rocky surface with hydrogen ice. 5. Neptune s atmosphere is the calmest in the solar system. 6. Pluto is the largest planet in the solar system. 7. Pluto is usually the ninth planet from the Sun. 8. Uranus has a horizontal axis. 9. Neptune s upper atmosphere is made up mostly of frozen hydrogen. 10. A Great Dark Spot, similar to the Great Red Spot of Jupiter, is one of the features of Uranus. 11. The Kuiper Belt contains about 70,000 stars. Skills: organizing information, comparing Complete the table below. Then, answer the questions. Planet Position Relative to the Sun THE OUTERMOST PLANETS Diameter Gases in Atmosphere Visited by a Probe? Pluto 1. 2. mostly methane 3. Neptune 4. 5. 6. yes Uranus 7. 8. 9. 10. 11. What did Voyager 2 discover about Neptune? 12. How much larger is Uranus s diameter than Neptune s? 13. What gas is found in the atmosphere of Neptune, Uranus, and Pluto? 14. Is it possible for Neptune to be the ninth planet from the Sun? Explain your answer. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 13

Naming Moons and Planets Enrichment Activity for Lessons 17-6, 17-8, and 17-9 Skills: researching, inferring PART A The planets and their moons are named for mythological (mith-uh-lahj-ih-kuhl) characters. Find out for which character each of the planets and moons listed below were named. Then, explain why you think each name was chosen. 1. Mercury 2. Venus 3. Mars 4. Pluto 5. Titan 6. Charon 7. Jupiter 8. Triton 9. Neptune _ 10. Saturn PART B Choose one of the mythological characters listed above that you would like to know more about. Use reference materials to find out more about your character. Present your findings to the class in a report. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 14

Comparing the Planets Enrichment Activity for Lessons 17-6, 17-8, and 17-9 Skills: comparing, researching PART A Use your text and reference materials to gather information about each planet s diameter, distance from the Sun, and number of moons. Write the information in the table below. Then, compare the information to rank the planets in each of these categories. Show the planet s rank by placing a number in the Rank column following each category. (The number 1 means that the planet has the largest number and 9 means that the planet has the smallest number in each category.) COMPARING PLANETS Planet Approximate Diameter Rank Distance from the Sun Rank Number of Known Moons Rank 1. Earth 2. Jupiter 3. Mars 4. Mercury 5. Neptune 6. Pluto 7. Saturn 8. Uranus 9. Venus PART B Use the information in the table to help answer the following questions. 1. What does the term diameter mean? 2. Which planet has the largest diameter? 3. Which planet has the smallest diameter? 4. Which planet is closest to the Sun? 5. Which planet is usually farthest from the Sun? 6. What is a moon? 7. a. Which planets have the fewest numbers of moons? b. How many moons do these planets have? _ 8. Which planet has the greatest number of known moons? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 15

17-10 What is a comet? PART A Match each term in Column B with its description in Column A. Write the correct letter in the space provided. Column A 1. lump of ice, frozen gas, and dust that orbits the Sun 2. head or solid part of a comet 3. gas cloud that surrounds the nucleus of a comet 4. long, ribbonlike trail of comet dust and gas 5. shape of a comet s orbit 6. cloud of inactive comets far beyond Pluto s orbit 7. cloud of inactive comets beyond Neptune s orbit Column B a. Kuiper Belt b. comet c. Oort Cloud d. nucleus e. ellipse f. coma g. tail Skills: diagramming, identifying On Figure A, draw tails on the comet to show how they change as the comet orbits the Sun. Then, on Figure B, label the parts of the comet. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 16

Chapter 17 Key Term Review Use the clues to complete the crossword puzzle. You will write letters in the shaded boxes. Clues Across 1. natural or artificial object orbiting another body in space 4. point in a planet s orbit at which it is farthest from the Sun 6. flattened circle, or oval 9. path of a planet around the Sun 11. rock or metal that enters Earth s atmosphere Down 1. the Sun and all the objects that orbit the Sun (two words) 2. broad, flat plains on the Moon 3. piece of rock or metal that falls on a planet or moon s surface 5. cloud of gas and dust in space 7. round hole on the Moon s surface 8. lump of ice, frozen gas, and dust that orbits the Sun 10. valley caused by a crack in the crust of a planet Building Science Vocabulary Write the letters from the shaded boxes in the spaces below. Then, use the clue to unscramble the letters and identify a term related to this chapter. CLUE: A natural satellite ANSWER: (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 17

Chapter 17 Test Interpreting Tables Use the table to answer the questions. Planet Diameter Number of Known Moons Rings Mercury 5,000 0 No Venus 12,000 0 No Earth 13,000 1 No Mars 7,000 2 No Jupiter 143,000 28 Yes Saturn 121,000 30 Yes Uranus 51,000 21 Yes Neptune 49,500 8 Yes Pluto 2,700 1 No 1. What is the smallest planet in the solar system? 2. Which planet is largest? 3. What are the two planets in our solar system that have only one moon? 4. What is true of all of the inner planets? 5. Which planet has the greatest number of known moons? 6. How is Pluto like the inner planets? 7. Which of the planets is about the same size as Earth? 8. List the planets in order from largest to smallest. Multiple Choice Write the letter of the term or phrase that best completes each statement. 1. The Great Red Spot is a feature of a. Earth. b. Jupiter. c. Saturn. d. Mars. 2. Jupiter is made up mostly of a. water. b. carbon dioxide. c. iron. d. hydrogen and helium. 3. The only planet known to have a covering of liquid water is a. Earth. b. Saturn. c. Pluto. d. Mars. 4. The farthest planet from the Sun is usually a. Saturn. b. Jupiter. c. Uranus. d. Pluto. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 18

Chapter 17 Test (continued) 5. The only planet that has not yet been visited by a space probe is a. Jupiter. b. Saturn. c. Mars. d. Pluto. 6. A body made up of rock, dust, gases, and ice that orbits the Sun is a a. comet. b. meteor. c. meteoroid. d. meteorite. 7. The curved path of one object around another in space is an a. apollo. b. orbit. c. aphelion. d. asteroid. 8. The force of attraction between all objects in the universe is a. nebula. b. perihelion. c. maria. d. gravity. 9. The point in a planet s orbit when it is closest to the Sun is a. aphelion. b. perihelion. c. maria. d. gravity. 10. Pluto s orbit sometimes takes it inside the orbit of a. Saturn. b. Uranus. c. Earth. d. Neptune. 11. Maria, craters, and mountains are features of a. Jupiter. b. Mars. c. Earth s Moon. d. comets. 12. Most asteroids are located between a. Earth and Mars. b. Mars and Jupiter. c. Mercury and the Sun. d. Venus and Neptune. 13. The Sun, together with the nine planets, make up the a. solar system. b. nebula. c. Big Bang. d. asteroid belt. 14. The speed at which a planet orbits the Sun is its a. orbital velocity. b. asteroid belt. c. perihelion. d. ellipse. 15. Earth is closest to the Sun in a. July. b. September. c. March. d. January. 16. A piece of rock or metal that strikes a planet s or moon s surface is a a. meteorite. b. meteor. c. meteoroid. d. meteor shower. 17. The hottest planet in the solar system is a. Earth. b. the Sun. c. Mercury. d. Venus. 18. The Mariner 10 space probe revealed many craters on the surface of a. the Moon. b. Venus. c. Mercury. d. Mars. 19. Mars has water in the form of a. rivers. b. water vapor. c. oceans. d. ice. 20. Unlike the other planets, the axis of Uranus is a. upside down. b. horizontal. c. vertical. d. tilted at a 23 angle. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 19

Chapter 17 Test (continued) Written Response Answer the following questions in complete sentences. 21. EXPLAIN: How does the aurora borealis form? 22. HYPOTHESIZE: Why did the astronauts who explored the Moon have to wear space suits? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 20

Answer Key CHAPTER 17: THE SOLAR SYSTEM 17-1 What is the solar system? 1. the Sun 2. nine 3. Mercury, Venus, Earth, Mars 4. Jupiter, Saturn, Uranus, Neptune, Pluto 5. curved path of one object around another object in space 6. Gravity caused a spinning cloud of gases and dust called a nebula to shrink to form the objects in the solar system. 1. Pluto 2. Neptune 3. Uranus 4. Saturn 5. Jupiter 6. Mars 7. Earth 8. Venus 9. Mercury 17-2 What do we know about orbits? PART A 1. All lines drawn from the center of a circle to its rim are the same length. An ellipse is oval-shaped, so lines drawn from the center of an ellipse to different points on its rim are different lengths. 2. elliptical 3. the speed at which a planet travels in its orbit 4. Gravitational attraction between two objects increases as the distance between them decreases. PART B 1. Perihelion 2. Aphelion 3. Aphelion 4. Aphelion 5. Perihelion 6. Perihelion 1. four 2. elliptical 3. A 4. F 5. D 17-2 What do we know about orbits? Enrichment Activity: Comparing Planetary Revolutions PART A 1. 88 Earth days 2. 225 Earth days 3. 365.25 Earth days 4. 687 Earth days 5. 11.86 Earth years 6. 29.46 Earth years 7. 84 Earth years 8. 165 Earth years 9. 248 Earth years PART B 1. Mercury 2. Pluto 3. The farther a planet is from the Sun, the longer its year is. The Big Idea 1. When you throw a ball, you give the ball a forward motion. At the same time, gravity pulls the ball toward the center of Earth. These two motions cause the ball to follow a curved path. 2. As the planets move in a curved path, they are pushed outward away from the Sun, which is similar to the outward pull you would feel swinging a ball tied to a string over your head. At the same time, gravity pulls the planets inward toward the Sun, and keeps them in a circular orbit, just as holding on to the string will keep the ball moving in a curved path around your head. 3. a. Gravity is the force that pulls objects toward Earth, which is the same force that every object in space exerts on every other object. b. Gravity pulls the planets toward the Sun at the same time that the motion of the planets in their orbit pushes the planets away from the Sun. These two opposite motions keeps the planets in their orbits. 1. The closer a planet is to the Sun, the shorter is its period of revolution. This is because the gravitational attraction between the planet and the Sun increases. 2. Accept answers in the range of 247 to 249 years old. 17-3 What do we know about Earth s Moon? 1. 1969 2. Apollo 17 3. one 4. one-sixth 5. atmosphere 6. maria, mountains (or highlands), craters 7. large objects striking its surface 8. erupting volcanoes 9. space suits 1. 1 lb 2. 60 lbs 3. 9 m 4. 1 m 5. 120 m 17-4 What are the other moons in the solar system? 1. natural or artificial body orbiting another body in space 2. Saturn 3. Mercury and Venus 4. Titan 5. Earth and Pluto 6. Jupiter (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 21

Answer Key 17-4 What are the other moons in the solar system? (continued) 1. Earth 2. Moon 3. 30 4. Titan 5. 2 6. 0 7. no moons 8. Neptune 9. 1 10. Uranus 11. Oberon, Miranda, Titania 12. Jupiter 13. Io, Callisto, Ganymede 14. Venus 15. 0 17-5 What do we know about Mercury, Venus, and Earth? 1. Mercury 2. from 430 C during daylight hours to 170 C during night 3. carbon dioxide 4. Its average temperature is higher than that of any other planet, and the air pressure is crushingly high. 5. It is retrograde, which means it spins in the opposite direction from most of the other planets. 6. Venus has smooth plains, mountains, and valleys. 7. liquid water, moderate temperatures, and an atmosphere containing oxygen 8. the iron in Earth s core 1. closest 2. craters 3. second 4. plains, mountains, and valleys 5. third 6. plains, mountains, valleys, and oceans 17-5 What do we know about Mercury, Venus, and Earth? Enrichment Activity: Earth Statistics PART A 1. about 4.6 billion years 2. 23 h, 56 min, 4.09 s 3. 365 days, 6 h, 9 min, and 9.54 s 4. 1 AU 5. 12,756 6. 281 K 7. Mount Everest 8. the Dead Sea PART B Check students drawings to make sure that the proportion of land to water is 30 percent to 70 percent. Be sure that they have included a key to indicate the colors used. 17-6 What do we know about Mars? 1. carbon dioxide 2. The water may be frozen beneath the Martian surface, or it may have boiled away in the thin atmosphere. 3. 687 days 4. The tilt of Mars s axis is similar to that of Earth. 5. It is reddish in color and has volcanoes, valleys, polar ice caps, craters, loose rocks, and river channels. 6. Olympus Mons 7. a large 4,000--long canyon on Mars s surface 1. Both 2. Mars 3. Both 4. Earth 5. Both 6. Both 7. Mars 8. Mars 9. Mars 10. Mars 17-7 What are asteroids and meteoroids? 1. an asteroid 2. meteorite 3. meteor 4. Mars and Jupiter 5. rock or metal or a combination of both 6. asteroids 7. crater 8. Ceres Check students diagrams. The orbit of the Trojan asteroids should follow Jupiter s orbit. The orbit of the asteroid belt should lie between Jupiter and Mars. The orbit of the near-earth asteroids should cross the orbits of Mars and Earth. 17-8 What do we know about Jupiter and Saturn? PART A 1. J 2. S 3. J 4. J 5. S 6. J 7. J 8. S PART B Students should place check marks beside items 1, 3, 4, 6, and 8. 1. Saturn; 121,000 2. Earth; 12,756 3. Jupiter; 143,000 17-9 What is known about Uranus, Neptune, and Pluto? 1. seventh 2. true 3. true 4. methane 5. windiest 6. smallest 7. true 8. true 9. methane 10. Neptune 11. rocks or ice fragments (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 22

Answer Key 17-9 What is known about Uranus, Neptune, and Pluto? (continued) 1. ninth 2. 2,200 3. no 4. eighth 5. 49,500 6. hydrogen, helium, methane 7. seventh 8. 51,000 9. hydrogen, helium, methane 10. yes 11. the Great Dark Spot 12. about 1,500 13. methane 14. Yes; When Pluto passes inside Neptune s orbit, Neptune becomes the ninth planet from the Sun. 17-9 What is known about Uranus, Neptune, and Pluto? Enrichment Activity: Naming Moons and Planets PART A Possible answers: 1. Mercury was the name of the Roman god of commerce, manual skill, travel, cleverness, and thievery. The planet may have been named for Mercury because of the speed at which it orbits the Sun. 2. Venus was the Roman goddess of beauty and love. Venus appears as a beautiful, bright body in the morning and evening sky. 3. Mars was the Roman god of war. Mars s red color may have reminded ancient astronomers of blood and violence. 4. Pluto was the Roman god who ruled over the lower worlds. Pluto s position at the farthest reaches of the solar system may have suggested this lower world. 5. The Titans were a Greek mythological race of deities who were overthrown by the Olympian gods. A titan refers to any person or thing of great size or power. The size of this moon of Saturn may have inspired this name. 6. In Greek mythology, Charon was the person who ferried souls of the dead across the river Styx to the underworld. Astronomers probably named Pluto s moon Charon because Charon was a servant of the god Pluto. 7. In Roman mythology, the god Jupiter ruled over all other gods and people. Astronomers probably gave the planet this name to acknowledge Jupiter as the largest planet. 8. In Greek mythology, Triton is the son of Poseidon (the Greek name for Neptune) and is described as having the head and upper body of a man and the tail of a fish. Astronomers may have considered this a fitting name for this moon of Neptune. 9. Neptune was the Roman god of the sea. Neptune s blue-green color may have suggested the sea. 10. Saturn was the Roman god of agriculture and the passage of time. At the time the planets were named, Saturn was the most distant and slow-moving planet known to astronomers. 17-9 What is known about Uranus, Neptune, and Pluto? (continued) Enrichment Activity: Naming Moons and Planets PART B Check students reports. Reports should include research about one mythological character. 17-9 What is known about Uranus, Neptune, and Pluto? Enrichment Activity: Comparing the Planets PART A Planet Approximate Diameter 1. Earth 13,000 2. Jupiter 143,000 3. Mars 7,000 4. Mercury 5,000 5. Neptune 49,500 6. Pluto 2,700 7. Saturn 121,000 8. Uranus 51,000 9. Venus 12,000 COMPARING PLANETS Rank Distance from the Sun 5 150 million 1 778 million 7 228 million 8 58 million 4 4.5 billion 9 5.9 billion 2 1.4 billion 3 2.9 billion 6 108 million Rank Number of Known Moons Rank 7 1 6 (tie) 5 28 2 6 2 5 9 0 8 (tie) 2 8 4 1 1 6 (tie) 4 30 1 3 21 3 8 0 8 (tie) PART B 1. distance across a circle or sphere at its widest point 2. Jupiter 3. Pluto 4. Mercury 5. Pluto 6. natural satellite that orbits a body in space 7. a. Mercury and Venus b. none 8. Saturn (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 23

Answer Key 17-10 What is a comet? 1. b 2. d 3. f 4. g 5. e 6. c 7. a On Figure A, check students drawings to make sure that the comet s tail appears to grow larger as the comet nears the Sun and that the tail points away from the Sun. Students should label Figure B as follows: 1. nucleus 2. coma 3. tail CHAPTER 17: THE SOLAR SYSTEM Key Term Review Across 1. satellite 4. aphelion 6. ellipse 9. orbit 11. meteor Down 1. solar system 2. maria 3. meteorite 5. nebula 7. crater 8. comet 10. rift Building Science Vocabulary Answer: Earth s Moon CHAPTER 17: THE SOLAR SYSTEM Chapter Test Interpreting Tables 1. Pluto 2. Jupiter 3. Earth and Pluto 4. They do not have rings. 5. Saturn 6. It lacks rings. 7. Venus 8. Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, and Pluto Multiple Choice l. b 2. d 3. a 4. d 5. d 6. a 7. b 8. d 9. b 10. d 11. c 12. b 13. a 14. a 15. d 16. a 17. d 18. c 19. d 20. b Written Response 21. Electrically charged particles from the Sun become trapped in Earth s magnetic field. When some of these particles escape the magnetic field and rain down on Earth, they strike atoms and molecules in the upper atmosphere and cause them to glow. 22. The Moon has no water, no atmosphere, and very extreme temperatures. The space suits provided the astronauts with oxygen to breathe and water to drink and protected them from the extreme heat and cold. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. The Solar System: CHAPTER 17, page 24