1. Chapter 18 Table of Contents Section 1 Astronomy: The Original Science
Studying Space
Table of Contents
Section 1 Astronomy: The Original Science
Section 2 Telescopes
Section 3 Mapping the Stars

2. Section 1 Astronomy: The Original Science
Chapter 18
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.

3. Objectives Chapter 18 Identify the units of a calendar.
Section 1 Astronomy: The Original Science
Chapter 18
Objectives
Identify the units of a calendar.
Describe two early ideas about the structure of the universe.
Describe the contributions of Brahe, Kepler, Galileo, Newton, and Hubble to modern astronomy.

4. Section 1 Astronomy: The Original Science
Chapter 18
Review 3/19/12
Name the important contributions to astronomy that were made by each of the following scientists:
Ptolemy
Copernicus
Brahe
Kepler
Newton
Hubble

5. Review 3/19/12 Chapter 18 What are the two types of telescopes?
Section 1 Astronomy: The Original Science
Chapter 18
Review 3/19/12
What are the two types of telescopes?
What does a lens do?
What is the electromagnetic spectrum?

6. Section 1 Astronomy: The Original Science
Chapter 18
Astronomy
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.

7. Chapter 18 Our Modern Calendar
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. Who’s Who of Early Astronomy
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. Who’s Who of Early Astronomy
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. Who’s Who of Early Astronomy, continued
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. Chapter 18 Modern Astronomy
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. Chapter 18
Section 2 Telescopes
Bellringer
Have you ever bent or slowed down light? Explain how.
Record your answer in your science journal.

13. Chapter 18
Section 2 Telescopes
Objectives
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.

14. Chapter 18
Section 2 Telescopes
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. Optical Telescopes Chapter 18
Section 2 Telescopes
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. Refracting and Reflecting Telescopes
Chapter 18
Section 2 Telescopes
Refracting and Reflecting Telescopes

17. Optical Telescopes, continued
Chapter 18
Section 2 Telescopes
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.

18. Optical Telescopes, continued
Chapter 18
Section 2 Telescopes
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

19. The Electromagnetic Spectrum
Chapter 18
Section 2 Telescopes
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.

20. The Electromagnetic Spectrum
Chapter 18
Section 2 Telescopes
The Electromagnetic Spectrum

21. Nonoptical Telescopes
Chapter 18
Section 2 Telescopes
Nonoptical Telescopes
Radio Telescopes Radio telescopes detect radio waves. Because radio wavelengths are much larger than optical wavelengths, radio telescopes must 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.

22. Nonoptical Telescopes, continued
Chapter 18
Section 2 Telescopes
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.

23. Chapter 18
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.

24. Chapter 18
Section 3 Mapping the Stars
Objectives
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.

25. Chapter 18 Patterns in the Sky
Section 3 Mapping the Stars
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.

26. Spring Constellations in the Northern Hemisphere
Chapter 18
Section 3 Mapping the Stars
Spring Constellations in the Northern Hemisphere

27. Finding Stars in the Night Sky
Chapter 18
Section 3 Mapping the Stars
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.

28. Zenith, Altitude, and Horizon
Chapter 18
Section 3 Mapping the Stars
Zenith, Altitude, and Horizon

29. Finding Stars in the Night Sky, continued
Chapter 18
Section 3 Mapping the Stars
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.

30. Chapter 18
Section 3 Mapping the Stars
The Celestial Sphere

31. Describing a Star’s Position
Chapter 18
Section 3 Mapping the Stars
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

32. The Size and Scale of the Universe
Chapter 18
Section 3 Mapping the Stars
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.

33. The Size and Scale of the Universe, continued
Chapter 18
Section 3 Mapping the Stars
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.

34. Chapter 18 The Doppler Effect
Section 3 Mapping the Stars
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.
This effect not only works with sound but also with light.

35. Chapter 18 The Doppler Effect
Section 3 Mapping the Stars
The Doppler Effect
As light source such as a star or galaxy is moving away from an observer, the light emitted looks redder than it normally does. This effect is called redshift.
If a light source is moving towards an observer then the light looks bluer than it normally does. This effect is called blueshift.
An Expanding Universe The Doppler effect has been used to discover that galaxies are rapidly moving apart from each other.

36. Red Shift Chapter 18 Section 3 Mapping the Stars
Click below to watch the Visual Concept.
You may stop the video at any time by pressing the Esc key.
Visual Concept

37. Chapter 18
Studying Space
Concept Map
Use the terms below to complete the concept map on the next slide.
declination
zenith
equator
horizon
celestial objects
altitude
celestial equator
astronomy

38. Chapter 18
Studying Space

39. Chapter 18
Studying Space

40. End of Chapter 18 Show

41. Chapter 18
Standardized Test Preparation
Reading
Read each of the passages. Then, answer the questions that follow each passage.

42. Chapter 18
Standardized Test Preparation
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
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

43. Chapter 18 Passage 1, continued In the mid-1500s,
Standardized Test Preparation
Passage 1, continued In the mid-1500s,
astronomers determined that there are actually 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.

44. Chapter 18
Standardized Test Preparation
1. According to the passage, which of the following years is a leap year?
A 46 BCE
B 1582
C 1600
D 1800

45. Chapter 18
Standardized Test Preparation
1. According to the passage, which of the following years is a leap year?
A 46 BCE
B 1582
C 1600
D 1800

46. Chapter 18 2. How long is a year? F 365 days G 365.224 days
Standardized Test Preparation
2. How long is a year?
F 365 days
G days
H days
I days

47. Chapter 18 2. How long is a year? F 365 days G 365.224 days
Standardized Test Preparation
2. How long is a year?
F 365 days
G days
H days
I days

48. Chapter 18 3. Why did Julius Caesar change the early Roman calendar?
Standardized Test Preparation
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

49. Chapter 18 3. Why did Julius Caesar change the early Roman calendar?
Standardized Test Preparation
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

50. 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. 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. Chapter 18 1. In the passage, what does archeoastronomer mean?
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. Chapter 18 1. In the passage, what does archeoastronomer mean?
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. 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. 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. Chapter 18 INTERPRETING GRAPHICS
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. Chapter 18
Standardized Test Preparation

58. 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. 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. 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. 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. Chapter 18 3. How would the wavelengths of light detected by observer
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. Chapter 18 3. How would the wavelengths of light detected by observer
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. Chapter 18
Standardized Test Preparation
MATH
Read each of the following questions, and choose the best answer.

65. 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. 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. 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 106 m
I 8 X 109 m

68. 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 106 m
I 8 X 109 m

69. 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. 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. 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. 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. 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 cm2 , which of the following estimates is the best estimate for the number of stars in 15 cm2 ?
A 700
B 900
C 1,200
D 1,350

74. 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 cm2 , which of the following estimates is the best estimate for the number of stars in 15 cm2 ?
A 700
B 900
C 1,200
D 1,350

75. Section 1 Astronomy: The Original Science
Chapter 18

76. Section 1 Astronomy: The Original Science
Chapter 18

77. Chapter 18
Standardized Test Preparation