1. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. How to Use This Presentation To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.” To advance through the presentation, click the right-arrow key or the space bar. From the resources slide, click on any resource to see a presentation for that resource. From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation. You may exit the slide show at any time by pressing the Esc key.

2. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter Presentation Transparencies Image and Math Focus Bank Bellringers Standardized Test Prep Visual Concepts Resources

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Studying Space Section 1 Astronomy: The Original Science Section 2 Telescopes Section 3 Mapping the Stars Chapter 18 Table of Contents

4. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Bellringer Choose a planet to research. Create a poster that features the planet and includes a cross section of the planet’s interior. Provide factual information and mythology about the planet on your poster. Chapter 18 Section 1 Astronomy: The Original Science

5. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 List the planets in the order in which they orbit the sun. Explain how scientists measure distances in space. Describe how the planets in our solar system were discovered. Describe three ways in which the inner planets and outer planets differ. Objectives Section 1 Astronomy: The Original Science

6. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Astronomy: The Original Science Chapter 18 People in ancient cultures used the seasonal cycles to determine when they should plant and harvest crops. They built observatories to study the night sky. Over time, the science of astronomy developed. Astronomy is the study of the universe. Astronomy

7. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Astronomy: The Original Science Chapter 18 Our Modern Calendar What Is Our Calendar Based On? The years, months, and days of our modern calendar are based on the observation of bodies in our solar system.

8. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Astronomy: The Original Science Chapter 18 Who’s Who of Early Astronomy Ptolemy: An Earth- Centered Universe Ptolemy thought that the Earth was at the center of the universe and that the other planets and the sun revolved around the Earth.

9. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Astronomy: The Original Science Chapter 18 Who’s Who of Early Astronomy Copernicus: A Sun- Centered Universe Copernicus thought the sun is at the center of the universe, and all of the planets—including the Earth—orbit the sun.

10. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Astronomy: The Original Science Chapter 18 Who’s Who of Early Astronomy, continued Tycho Brahe: A Wealth of Data In the late- 1500s, Danish astronomer Tycho Brahe made the most detailed astronomical observations that had ever been recorded. Johannes Kepler: Laws of Planetary Motion Johannes Kepler stated three laws of planetary motion. These laws are still used today.

11. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Astronomy: The Original Science Chapter 18 Modern Astronomy Milestones in Modern Astronomy The invention of the telescope and the discovery of gravity were two milestones in the development of modern astronomy. Edwin Hubble: Beyond the Edge of the Milky Way In 1924, Edwin Hubble proved that other galaxies existed beyond the edge of the Milky Way.

12. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Bellringer Have you ever bent or slowed down light? Explain how. Record your answer in your science journal. Chapter 18

13. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Chapter 18 Compare refracting telescopes with reflecting telescopes. Explain how the atmosphere limits astronomical observations, and explain how astronomers overcome these limitations. List the types of electromagnetic radiation that astronomers use to study objects in space. Objectives

14. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Chapter 18 Telescopes A Telescope is an instrument that gathers electromagnetic radiation from objects in space and concentrates it for better observation. There are many different types of telescopes.

15. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Chapter 18 Optical Telescopes Refracting Telescopes Telescopes that use lenses to gather and focus light are called refracting telescopes. A refracting telescope is shown on the next slide. Reflecting Telescope A telescope that uses a curved mirror to gather and focus light is called a reflecting telescope. A reflecting telescope is shown on the next slide.

16. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Chapter 18 Optical Telescopes Refracting Telescopes Telescopes that use lenses to gather and focus light are called refracting telescopes. A refracting telescope is shown on the next slide. Reflecting Telescope A telescope that uses a curved mirror to gather and focus light is called a reflecting telescope. A reflecting telescope is shown on the next slide.

17. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Chapter 18 Refracting and Reflecting Telescopes

18. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Chapter 18 Optical Telescopes, continued Very Large Reflecting Telescopes In some very large reflecting telescopes, several mirrors work together to collect light and focus it in the same area.

19. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Chapter 18 Optical Telescopes, continued Optical Telescopes and the Atmosphere The light gathered by telescopes on the Earth is affected by the atmosphere. Optical Telescopes in Space To avoid interference by the atmosphere, scientists have put telescopes in space

20. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Chapter 18 The Electromagnetic Spectrum What Is the Electromagnetic Spectrum? The electromagnetic spectrum is made up of all of the wavelengths of electromagnetic radiation. Detecting Electromagnetic Radiation Visible light is only a small band of the electromagnetic spectrum. Radio waves, microwaves, infrared light, ultraviolet light, X rays, and gamma rays— are invisible to the human eye.

21. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Chapter 18 The Electromagnetic Spectrum

22. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Chapter 18 Nonoptical Telescopes Radio Telescopes Radio telescopes detect radio waves. Because radio wavelengths are much larger than optical wavelengths, radio telescopes much be very large. Linking Radio Telescopes Astronomers can get more detailed images of the universe by linking radio telescopes together. Working together, the telescopes function as a single giant telescope.

23. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Telescopes Chapter 18 Nonoptical Telescopes, continued Nonoptical Telescopes in Space Because most electromagnetic waves are blocked by the Earth’s atmosphere, scientists have placed ultraviolet telescopes, infrared telescopes, gamma-ray telescopes, and X-ray telescopes in space.

24. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 Mapping the Stars Bellringer Is it possible to determine the direction of the North Pole just by looking at the stars? Explain your answer. Write your answer in your science journal. Chapter 18

25. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 Mapping the Stars Chapter 18 Explain how constellations are used to organize the night sky. Describe how the altitude of a star is measured. Explain how the celestial sphere is used to describe the location of objects in the sky. Compare size and scale in the universe, and explain how red shift indicates that the universe is expanding. Objectives

26. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 Mapping the Stars Chapter 18 Patterns in the Sky Constellations Help Organize the Sky A constellation is a region of the sky. Each constellation shares a border with neighboring constellations. A constellation map is shown on the next slide. Seasonal Changes As Earth revolves around the sun, the apparent locations of the constellations change from season to season.

27. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Spring Constellations in the Northern Hemisphere Section 3 Mapping the Stars

28. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 Mapping the Stars Chapter 18 Finding Stars in the Night Sky You can describe the location of a star or planet by using an instrument called an astrolabe and the following points of reference: The zenith is the point in the sky directly above on observer on Earth. The altitude is the angle between an object in the sky and the horizon. The horizon is the line where the sky and the Earth appear to meet.

29. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Zenith, Altitude, and Horizon Section 3 Mapping the Stars

30. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 Mapping the Stars Chapter 18 Finding Stars in the Night Sky, continued Using an astrolabe allows you to describe where a star or planet is relative to you. Scientists need a different method that describes location independently of the observer’s location. Astronomers describe the location of a star or planet in terms of the celestial sphere.

31. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 The Celestial Sphere Section 3 Mapping the Stars

32. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 Mapping the Stars Chapter 18 Describing a Star’s Position Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

33. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 Mapping the Stars Chapter 18 The Size and Scale of the Universe In the 1600s, Nicolaus Copernicus noticed that the planets appeared to move relative to each other but that the stars did not. Thus, he thought that the stars must be much farther away than the planets. Measuring Distance in Space A light-year is a unit of length equal to the distance that light travels in 1 year.

34. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 Mapping the Stars Chapter 18 The Size and Scale of the Universe, continued It is important to consider scale when thinking about the universe. Although stars looks tiny in the night sky, remember that they are actually a lot larger than Earth.

35. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 Mapping the Stars Chapter 18 The Doppler Effect What Is the Doppler Effect? Have you ever noticed that when a driver in an approaching car blows the horn, the horn sounds higher pitched as the car approaches and lower pitched after the car passes? This effect is called the Doppler effect. An Expanding Universe The Doppler effect has been used to discover that galaxies are rapidly moving apart from each other.

36. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 Mapping the Stars Chapter 18 Red Shift Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

37. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Studying Space Concept Map Use the terms below to complete the concept map on the next slide. Chapter 18 declination zenith equator horizon celestial objects altitude celestial equator astronomy

38. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Studying Space Chapter 18

39. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Studying Space Chapter 18

40. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Chapter 18 Show

41. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Reading Read each of the passages. Then, answer the questions that follow each passage. Chapter 18 Standardized Test Preparation

42. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Passage 1 In the early Roman calendar, a year had exactly 365 days. The calendar worked well until people realized that the seasons were beginning and ending later each year. To fix this problem, Julius Caesar developed the Julian calendar based on a 365.25-day calendar year. He added 90 days to the year 46 BCE and added an extra day every 4 years. A year in which an extra day is added to the calendar is called a leap year. Continued on next slide Chapter 18 Standardized Test Preparation

43. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Passage 1, continued In the mid-1500s, astronomers determined that there are actually 365.2422 days in a year, so Pope Gregory XIII developed the Gregorian calendar. He dropped 10 days from the year 1582 and restricted leap years to years that are divisible by 4 but not by 100 (except for years that are divisible by 400). Today, most countries use the Gregorian calendar. Chapter 18 Standardized Test Preparation

44. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. 1. According to the passage, which of the following years is a leap year? A 46 BCE B 1582 C 1600 D 1800 Chapter 18 Standardized Test Preparation

45. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. 1. According to the passage, which of the following years is a leap year? A 46 BCE B 1582 C 1600 D 1800 Chapter 18 Standardized Test Preparation

46. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. 2. How long is a year? F 365 days G 365.224 days H 365.2422 days I 365.25 days Chapter 18 Standardized Test Preparation

47. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. 2. How long is a year? F 365 days G 365.224 days H 365.2422 days I 365.25 days Chapter 18 Standardized Test Preparation

48. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. 3. Why did Julius Caesar change the early Roman calendar? A to deal with the fact that the seasons were beginning and ending later each year B to compete with the Gregorian calendar C to add an extra day every year D to shorten the length of a year Chapter 18 Standardized Test Preparation

49. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. 3. Why did Julius Caesar change the early Roman calendar? A to deal with the fact that the seasons were beginning and ending later each year B to compete with the Gregorian calendar C to add an extra day every year D to shorten the length of a year Chapter 18 Standardized Test Preparation

50. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation Passage 2 The earliest known evidence of astronomical observations is a group of stones near Nabta in southern Egypt that is between 6,000 and 7,000 years old. According to archeoastronomers, some of the stones are positioned such that they would have lined up with the sun during the summer solstice 6,000 years ago. The summer solstice occurs on the longest day of the year. At the Nabta site, the noonday sun is at its zenith (directly overhead) for about three weeks before and after the summer solstice. Continued on next slide

51. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation Passage 2, continued When the sun is at its zenith, upright objects do not cast shadows. For many civilizations in the Tropics, the zenith sun has had ceremonial significance for thousands of years. The same is probably true for the civilizations that used the Nabta site. Artifacts found at the site near Nabta suggest that the site was created by African cattle herders. These people probably used the site for many purposes, including trade, social bonding, and ritual.

52. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 1. In the passage, what does archeoastronomer mean? A an archeologist that studies Egyptian culture B an astronomer that studies the zenith sun C an archeologist that studies ancient astronomy D an astronomer that studies archeologists

53. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 1. In the passage, what does archeoastronomer mean? A an archeologist that studies Egyptian culture B an astronomer that studies the zenith sun C an archeologist that studies ancient astronomy D an astronomer that studies archeologists

54. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 2. Why don’t upright objects cast a shadow when the sun is at its zenith? F because the sun is directly overhead G because the summer solstice is occurring H because the sun is below the horizon I because the sun is at its zenith on the longest day of the year

55. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 2. Why don’t upright objects cast a shadow when the sun is at its zenith? F because the sun is directly overhead G because the summer solstice is occurring H because the sun is below the horizon I because the sun is at its zenith on the longest day of the year

56. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation INTERPRETING GRAPHICS The diagram on the following slide shows a galaxy moving in relation to four observers. The concentric circles illustrate the Doppler effect at each location. Use the diagram to answer the questions that follow.

57. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation

58. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 1. Which of the following observers would see the light from the galaxy affected by redshift? A observers 1 and 2 B observer 3 C observers 3 and 4 D observers 1 and 4

59. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 1. Which of the following observers would see the light from the galaxy affected by redshift? A observers 1 and 2 B observer 3 C observers 3 and 4 D observers 1 and 4

60. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 2. Which of the following observers would see the light from the galaxy affected by blueshift? F observer 1 G observers 2 and 4 H observers 3 and 4 I observer 2

61. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 2. Which of the following observers would see the light from the galaxy affected by blueshift? F observer 1 G observers 2 and 4 H observers 3 and 4 I observer 2

62. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 3. How would the wavelengths of light detected by observer 4 appear? A The wavelengths would appear shorter than they really are. B The wavelengths would appear longer than they really are. C The wavelengths would appear unchanged. D The wavelengths would alternate between blue and red.

63. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 3. How would the wavelengths of light detected by observer 4 appear? A The wavelengths would appear shorter than they really are. B The wavelengths would appear longer than they really are. C The wavelengths would appear unchanged. D The wavelengths would alternate between blue and red.

64. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation MATH Read each of the following questions, and choose the best answer.

65. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 1. If light travels 300,000 km/s, how long does light reflected from Mars take to reach Earth when Mars is 65,000,000 km away? A 22 s B 217 s C 2,170 s D 2,200 s

66. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 1. If light travels 300,000 km/s, how long does light reflected from Mars take to reach Earth when Mars is 65,000,000 km away? A 22 s B 217 s C 2,170 s D 2,200 s

67. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 2. Star A is 8 million kilometers from star B. What is this distance expressed in meters? F 0.8 m G 8,000 m H 8 X 10 6 m I 8 X 10 9 m

68. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 2. Star A is 8 million kilometers from star B. What is this distance expressed in meters? F 0.8 m G 8,000 m H 8 X 10 6 m I 8 X 10 9 m

69. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 3. If each hexagonal mirror in the Keck Telescopes is 1.8 m across, how many mirrors would be needed to create a light-reflecting surface that is 10.8 m across? A 3.2 B 5 C 6 D 6.2

70. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 3. If each hexagonal mirror in the Keck Telescopes is 1.8 m across, how many mirrors would be needed to create a light-reflecting surface that is 10.8 m across? A 3.2 B 5 C 6 D 6.2

71. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 4. If the altitude of a star is 37°, what is the angle between the star and the zenith? F 143° G 90° H 53° I 37°

72. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 4. If the altitude of a star is 37°, what is the angle between the star and the zenith? F 143° G 90° H 53° I 37°

73. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 5. You are studying an image made by the Hubble Space Telescope. If you observe 90 stars in an area that is 1 cm 2, which of the following estimates is the best estimate for the number of stars in 15 cm 2 ? A 700 B 900 C 1,200 D 1,350

74. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation 5. You are studying an image made by the Hubble Space Telescope. If you observe 90 stars in an area that is 1 cm 2, which of the following estimates is the best estimate for the number of stars in 15 cm 2 ? A 700 B 900 C 1,200 D 1,350

75. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Astronomy: The Original Science Chapter 18

76. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Astronomy: The Original Science Chapter 18

77. ResourcesChapter menu Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 18 Standardized Test Preparation