1. Chapter 27 The Sun-Earth-Moon System
Section 1: Tools of Astronomy
Section 2: The Moon
Section 3: The Sun-Earth-Moon System

2. Section 1: Tools of Astronomy
Radiation emitted or reflected by distant objects allows scientists to study the universe. K
What I Know W
What I Want to Find Out L
What I Learned

3. Essential Questions What is electromagnetic radiation?
How do telescopes work?
How does space exploration help scientists learn about the universe?
Tools of Astronomy
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4. Vocabulary Review New refraction electromagnetic spectrum
refracting telescope
reflecting telescope
interferometry
Tools of Astronomy
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5. Radiation
The radiation from bodies throughout the universe that scientists study is called electromagnetic radiation.
This includes visible light, infrared and ultraviolet radiation, radio waves, microwaves, X rays, and gamma rays.
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Tools of Astronomy

6. Radiation
The electromagnetic spectrum consists of all types of electromagnetic radiation arranged according to wavelength and frequency.
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Tools of Astronomy

7. Radiation Wavelength and frequency
Electromagnetic radiation is classified by wavelength, the distance between peaks on a wave, and frequency, the number of waves or oscillations that pass a given point per second.
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Tools of Astronomy

8. Radiation Wavelength and frequency
Frequency is related to wavelength by the mathematical relationship c = λf, where c is the speed of light (3.0 × 108 m/s), λ is the wavelength, and f is the frequency.
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Tools of Astronomy

9. Telescopes
Telescopes provide the ability to observe wavelengths beyond what the human eye can detect. They collect electromagnetic radiation from distant objects and focus it so that an image of the object can be recorded.
Telescopes can also collect light over periods of minutes or hours.
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Tools of Astronomy

10. Telescopes Refracting and reflecting telescopes
Refracting telescopes use lenses to focus visible light.
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Tools of Astronomy

11. Telescopes Refracting and reflecting telescopes
Reflecting telescopes use mirrors to focus visible light.
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Tools of Astronomy

12. Telescopes Telescopes using non-visible wavelengths
For all telescopes, the goal is to bring as much electromagnetic radiation as possible into focus.
Infrared and ultraviolet radiation can be focused by mirrors in a way similar to that used for visible light.
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Tools of Astronomy

13. Telescopes Telescopes using non-visible wavelengths
X rays cannot be focused by normal mirrors, and thus special designs must be used.
Gamma rays cannot be focused, so telescopes designed to detect this type of radiation can determine only the direction from which the rays come.
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Tools of Astronomy

14. Telescopes Telescopes using non-visible wavelengths
A radio telescope collects the longer wavelengths of radio waves with a large dish antenna and reflects them to a point above the dish. There, a receiver converts the radio waves into electric signals that can be stored in a computer for analysis.
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Tools of Astronomy

15. Telescopes Telescopes using non-visible wavelengths
The data collected from radio telescopes are converted into visual images by a computer. The image resolution can be improved using interferometry, a process that links separate telescopes so they act as one telescope, producing more detailed images as the distance between the telescopes increases.
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Tools of Astronomy

16. Space-Based Astronomy
Space-based telescopes allow astronomers to study radiation that would be blurred by our atmosphere.
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Tools of Astronomy

17. Space-Based Astronomy
Hubble Space Telescope
The Hubble Space Telescope was designed to obtain sharp visible-light images without atmospheric interference and to make observations in infrared and ultraviolet wavelengths.
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Tools of Astronomy

18. Space-Based Astronomy
Spacecraft
Spacecraft make observations from above Earth’s atmosphere and can also be sent directly to the bodies being observed.
Robotic probes are spacecraft that can make close-up observations and sometimes land to collect information directly.
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Tools of Astronomy

19. Space-Based Astronomy
Human spaceflight
The most recent human studies have been accomplished with the space shuttle program between 1981 and 2011.
The space shuttle provides an environment for scientists to study the effects of weightlessness on humans, plants, the growth of crystals, and other phenomena.
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Tools of Astronomy

20. Spinoff technology
Many technologies that were originally developed for use in space programs are now used by people around the world. More than different NASA technologies, such as memory foam, have been passed on to commercial industries for common use; these are called spinoffs.
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Tools of Astronomy

21. Review Essential Questions Vocabulary
What is electromagnetic radiation?
How do telescopes work?
How does space exploration help scientists learn about the universe?
Vocabulary
electromagnetic spectrum
refracting telescope
reflecting telescope
interferometry
Tools of Astronomy
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23. Section 2: The Moon
The Moon, Earth’s nearest neighbor in space, is unique among the moons in our solar system. K
What I Know W
What I Want to Find Out L
What I Learned

24. Essential Questions What is the history of lunar exploration?
How are lunar properties and structures described?
What are the features of the Moon?
What is the theory of the Moon’s origin and formation?
The Moon
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25. Vocabulary Review New lava albedo highland maria impact crater ejecta
ray
rille
regolith
The Moon
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26. Exploring the Moon
Astronomers have learned much about the Moon from observations with telescopes. However, most knowledge of the Moon comes from explorations by space probes and from landings by astronauts.
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The Moon

27. Exploring the Moon
The first step toward reaching the Moon was in 1957, when the Soviet Union launched the first artificial satellite, Sputnik I.
Four years later, Soviet cosmonaut Yuri A. Gagarin became the first human in space.
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The Moon

28. Exploring the Moon
In 1957, the United States launched the first American, Alan B. Shepard, Jr., into space during Project Mercury.
This was followed by Project Gemini that launched two-person crews.
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The Moon

29. Exploring the Moon
On July 20, 1969, the Apollo program landed Neil Armstrong and Edwin “Buzz” Aldrin on the Moon during the Apollo 11 mission.
Scientists hope to return to the Moon someday and eventually establish a permanent base there.
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The Moon

30. Albedo – the percentage of incoming sunlight the surface reflects
The Lunar Surface
Albedo – the percentage of incoming sunlight the surface reflects
Moon – 7%
Earth – 31%
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The Moon

31. Lunar highlands are heavily cratered, light in color and mountainous.
The Lunar Surface
Lunar highlands are heavily cratered, light in color and mountainous.
Maria are dark, smooth plains, which average 3 km lower in elevation and have few craters.
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The Moon

32. The Lunar Surface Lunar craters
The craters on the Moon, called impact craters, formed when objects from space crashed into the lunar surface.
The material blasted out during these impacts fell back to the Moon’s surface as ejecta.
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The Moon

33. The Lunar Surface Lunar craters
Some craters have long trails of ejecta, called rays, that radiate outward from the impact site.
Rilles are valleylike structures that might be collapsed lava tubes.
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The Moon

34. The Moon is important because:
The Lunar Surface
Lunar properties
Earth’s moon is unique among all the moons in the solar system. It is the largest moon compared to the radius and mass of the planet it orbits. It is a solid, rocky body, in contrast with the icy compositions of most other moons of the solar system.
The Moon’s orbit is farther from Earth relative to the distance of many moons from the planets they orbit.
The Moon is important because:
It stabilizes the tilt of the Earth’s axis which regulates climate.
It could prevent Earth impacts.
It causes tides.
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The Moon

35. The Lunar Surface Lunar properties
The Moon is made up of minerals similar to those of Earth—mostly silicates.
The highlands are mostly lunar breccias, which are rocks formed by the fusion of smaller rocks during impacts. The maria are predominantly basalt that contains no water.
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The Moon

36. Add link to Interactive Table from p. 772 here.
The Moon and Earth
Concepts In Motion
FPO
Add link to Interactive Table from p. 772 here.
The Moon
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37. History of the Moon
The Moon is approximately 3.8 to 4.6 billion years old, about the same age as Earth.
Scientists theorize that the Moon was heavily bombarded during its first 800 million years. This caused the breaking and heating of surface rocks and resulted in a layer of loose, ground-up rock called regolith on the surface.
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The Moon

38. History of the Moon Layered structure
Scientists infer from seismic data that the Moon, like Earth, has a layered structure, which consists of the crust, upper mantle, lower mantle, and core.
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The Moon

39. History of the Moon Formation of maria
After the period of intense bombardment that formed the highlands, lava welled up from the Moon’s interior and filled in the large impact basins.
This lava fill created the dark, smooth plains of the maria.
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The Moon

40. History of the Moon Tectonics
Scientists think that the Moon is not tectonically active because the Moon has no active volcanoes and no significant magnetic field.
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The Moon

41. Moon Formation
The Moon probably formed as the result of a collision between Earth and a Mars-sized object about 4.5 bya when the solar system was forming.
Draw:
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The Moon

42. Formation
The impact theory of the Moon’s formation states that material ejected from Earth and from the striking object eventually merged to form the Moon.
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The Moon

43. Add link to Animation from p. 774 here.
Moon Impact Theory
Concepts In Motion
FPO
Add link to Animation from p. 774 here.
The Moon
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44. Review Essential Questions Vocabulary
What is the history of lunar exploration?
How are lunar properties and structures described?
What are the features of the Moon?
What is the theory of the Moon’s origin and formation?
Vocabulary
albedo
highland
maria
impact crater
ejecta
ray
rille
regolith
The Moon
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46. Section 3: The Sun-Earth-Moon System
Motions of the Sun-Earth-Moon system define Earth’s day, month, and year. K
What I Know W
What I Want to Find Out L
What I Learned

47. Essential Questions
What are the relative positions and motions of the Sun, Earth, and Moon?
What are the phases of the Moon?
What are the differences between solstices and equinoxes?
How are eclipses of the Sun and Moon explained?
The Sun-Earth-Moon System
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48. Vocabulary Review New revolution ecliptic plane solstice equinox
synchronous rotation
solar eclipse
perigee
apogee
lunar eclipse
The Sun-Earth-Moon System
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49. The Sun-Earth-Moon System
The Sun provides light and warmth, and it is the source of most of the energy that fuels our society.
The Moon causes tides in our oceans and illuminates our sky with its monthly cycle of phases.
Every society from ancient times to the present has based its calendar and its timekeeping system on the apparent motions of the Sun and Moon.

50. Celestial objects appear to rise in the East in set in the West.
Daily Motions
The Sun, the Moon, planets, and stars do not orbit around Earth every day. It appears that way because we observe the sky from a planet that rotates 15 degrees every hour.
Celestial objects appear to rise in the East in set in the West.
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The Sun-Earth-Moon System

51. Daily Motions Earth’s rotation
Both a Foucault pendulum and the Coriolis effect demonstrate that Earth is rotating.
The time period from one noon to the next is called a solar day. As Earth rotates, it moves in its orbit and has to turn a little farther each day to align with the Sun.
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The Sun-Earth-Moon System

52. Annual Motions
Earth orbits the Sun in a slightly elliptical orbit. The plane of Earth’s orbit around the sun is called the ecliptic plane.
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The Sun-Earth-Moon System

53. Annual Motions The effects of Earth’s tilt
Earth’s axis is tilted relative to the ecliptic at approximately 23.5°. As Earth orbits the Sun, the orientation of Earth’s axis remains fixed. This causes the seasons.
Draw & Label:
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The Sun-Earth-Moon System

54. Annual Motions The effects of Earth’s tilt
Earth’s tilt and orbital motion around the Sun result in a cycle of the seasons.
Another effect is the changing angle of the Sun above the horizon from summer to winter.
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The Sun-Earth-Moon System

55. Annual Motions The effects of Earth’s tilt
At a solstice, the Sun is overhead at its farthest distance either north or south of the equator.
The lines of latitude that correspond to these positions on Earth have been identified as the Tropic of Cancer and the Tropic of Capricorn.
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The Sun-Earth-Moon System

56. Annual Motions The effects of Earth’s tilt
The summer solstice occurs in the northern hemisphere when the Sun is directly overhead at the Tropic of Cancer, 23.5° north latitude.
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The Sun-Earth-Moon System

57. Annual Motions The effects of Earth’s tilt
The winter solstice occurs in the northern hemisphere when the Sun is directly overhead at the Tropic of Capricorn, 23.5° south latitude.
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The Sun-Earth-Moon System

58. Annual Motions The effects of Earth’s tilt
At an equinox, Earth’s axis is perpendicular to the Sun’s rays and at noon the Sun is directly overhead at the equator.
The Sun’s maximum height, called its zenith, varies throughout the year depending on the viewer’s location.
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The Sun-Earth-Moon System

59. Annual Motions The effects of Earth’s tilt
For a person standing on the 23.5° north latitude, the Sun would be at zenith on the summer solstice. It would be at its lowest position at the winter solstice.
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The Sun-Earth-Moon System

60. Phases of the Moon
The Moon changes position relative to the ecliptic plane as it orbits Earth.
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The Sun-Earth-Moon System

61. Phases of the Moon Waxing and waning
Starting at the new moon, as the Moon moves in its orbit around Earth, more of the sunlit side of the Moon becomes visible. This increase in the visible sunlit surface of the Moon is called the waxing phase.
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The Sun-Earth-Moon System

62. Phases of the Moon Waxing and waning
The waxing phases are called waxing crescent, first quarter, and waxing gibbous.
As the Moon moves to the far side of Earth from the Sun, the entire sunlit side of the Moon faces Earth. This is known as a full moon.
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The Sun-Earth-Moon System

63. Phases of the Moon Waxing and waning
After the full moon, the portion of the sunlit side that is visible begins to decrease. This is called the waning phase. The waning phases are waning gibbous and waning crescent. When exactly half of the sunlit portion is visible, it is called the third quarter.
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The Sun-Earth-Moon System

64. Visualizing the Phases of the Moon
One-half of the Moon is always illuminated by the Sun’s light, but the entire lighted half is visible from Earth only at full moon. The rest of the time you see portions of the lighted half. These portions are called lunar phases.
Waxing – lit portion of the Moon appears to be getting larger.
Waning – lit portion of the Moon appears to be getting smaller.
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The Sun-Earth-Moon System

65. Add link to Animation from p. 779 here.
Visualizing the Phases of the Moon
Concepts In Motion
FPO
Add link to Animation from p. 779 here.
The Sun-Earth-Moon System
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66. Phases of the Moon
Synchronous rotation
The state at which the Moon’s orbital and rotational periods are equal is called synchronous rotation.
As the Moon orbits Earth, the same side faces Earth at all times because the Moon spins exactly once each time it goes around Earth.
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The Sun-Earth-Moon System

67. Lunar Motions
The length of time it takes for the Moon to go through a complete cycle of phases is called a lunar month.
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The Sun-Earth-Moon System

68. Lunar Motions
The length of a lunar month is about 29.5 days, which is longer than the 3 days it takes for one revolution, or orbit, around Earth.
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The Sun-Earth-Moon System

69. Lunar Motions
The Moon rotates as it revolves, keeping the same side facing Earth.
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The Sun-Earth-Moon System

70. Lunar Motions
Tides
The Moon’s gravity pulls on Earth along an imaginary line connecting Earth and the Moon, and this creates bulges of ocean water on both the near and far sides of Earth.
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The Sun-Earth-Moon System

71. Neap tides are smaller and Spring tides are larger than average.
Special Tides (Draw)
Neap tides are smaller and Spring tides are larger than average.
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The Sun-Earth-Moon System

72. Solar Eclipses
A solar eclipse occurs when the Moon passes directly between the Sun and Earth and blocks the Sun from view.
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The Sun-Earth-Moon System

73. Solar Eclipses How solar eclipses occur
During a solar eclipse, the Moon passes between Earth and the Sun. Those on Earth within the darkest part of the Moon’s shadow (umbra) see a total eclipse. Those within the lighter part, or penumbral shadow, see only a partial eclipse.
Draw:
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The Sun-Earth-Moon System

74. Add link to Animation from p. 782 here.
Eclipse
Concepts In Motion
FPO
Add link to Animation from p. 782 here.
The Sun-Earth-Moon System
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75. Solar Eclipses How solar eclipses occur
Solar eclipses can take place only when the Earth, the Moon, and the Sun are perfectly aligned.
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The Sun-Earth-Moon System

76. Solar Eclipses How solar eclipses occur
Solar eclipses can happen only when the Moon’s orbital plane and ecliptic plane intersect along the Sun-Earth line, shown on the right. In the left diagram, this does not happen, and the Moon’s shadow misses Earth.
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The Sun-Earth-Moon System

77. Solar Eclipses How solar eclipses occur
The closest point in the Moon’s orbit to Earth is called perigee.
The farthest point is called apogee.
An annular eclipse takes place when the Moon is too far away for its umbral shadow to reach Earth.
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The Sun-Earth-Moon System

78. Lunar Eclipses
A lunar eclipse occurs when the Moon passes through Earth’s shadow.
A total lunar eclipse occurs when the entire Moon is within Earth’s umbra. This lasts for approximately two hours.
Draw:
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The Sun-Earth-Moon System

79. Lunar Eclipses
Lunar eclipses do not occur every full moon because the Moon in its orbit usually passes above or below the Sun as seen from Earth.
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The Sun-Earth-Moon System

80. Review Essential Questions Vocabulary
What are the relative positions and motions of the Sun, Earth, and Moon?
What are the phases of the Moon?
What are the differences between solstices and equinoxes?
How are eclipses of the Sun and Moon explained?
Vocabulary
ecliptic plane
solstice
equinox
synchronous rotation
solar eclipse
perigee
apogee
lunar eclipse
The Sun-Earth-Moon System
Copyright © McGraw-Hill Education