2. 27 The Sun-Earth-Moon System Section 27.1: Tools of Astronomy
Section 27.2: The Moon
Section 27.3: The Sun-Earth-Moon System

3. Objectives Define electromagnetic radiation.
Section 27.1
Tools of Astronomy
Objectives
Define electromagnetic radiation.
Explain how telescopes work.
Describe how space exploration helps scientists learn about the universe.

4. Section 27.1
Tools of Astronomy
Radiation emitted or reflected by distant objects allows scientists to study the universe.
Review Vocabulary
refraction: occurs when a light ray changes direction as it passes from one material into another

5. New Vocabulary Tools of Astronomy electromagnetic spectrum
Section 27.1
Tools of Astronomy
New Vocabulary
electromagnetic spectrum
refracting telescope
reflecting telescope
interferometry

6. Section 27.1
Tools of Astronomy
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.

7. Section 27.1
Tools of Astronomy
Radiation
The electromagnetic spectrum consists of all types of electromagnetic radiation arranged according to wavelength and frequency.

8. Radiation Wavelength and frequency
Section 27.1
Tools of Astronomy
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.

9. Radiation Wavelength and frequency
Section 27.1
Tools of Astronomy
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.

10. Section 27.1
Tools of Astronomy
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.

11. Telescopes Refracting and reflecting telescopes
Section 27.1
Tools of Astronomy
Telescopes
Refracting and reflecting telescopes
Refracting telescopes use lenses to focus visible light.

12. Telescopes Refracting and reflecting telescopes
Section 27.1
Tools of Astronomy
Telescopes
Refracting and reflecting telescopes
Reflecting telescopes use mirrors to focus visible light.

13. Telescopes Telescopes using non-visible wavelengths
Section 27.1
Tools of Astronomy
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.

14. Telescopes Telescopes using non-visible wavelengths
Section 27.1
Tools of Astronomy
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.

15. Telescopes Telescopes using non-visible wavelengths
Section 27.1
Tools of Astronomy
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.

16. Telescopes Telescopes using non-visible wavelengths
Section 27.1
Tools of Astronomy
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.

17. Space-Based Astronomy
Section 27.1
Tools of Astronomy
Space-Based Astronomy
Space-based telescopes allow astronomers to study radiation that would be blurred by our atmosphere.

18. Space-Based Astronomy
Section 27.1
Tools of Astronomy
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.

19. Section 27.1
Tools of Astronomy
Please click the image above to view the interactive table.

20. Space-Based Astronomy
Section 27.1
Tools of Astronomy
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.

21. Space-Based Astronomy
Section 27.1
Tools of Astronomy
Space-Based Astronomy
Human spaceflight
The space shuttle provides an environment for scientists to study the effects of weightlessness on humans, plants, the growth of crystals, and other phenomena.
Because shuttle missions last a maximum of just 17 days, long-term effects must be studied in space stations.

22. Space-Based Astronomy
Section 27.1
Tools of Astronomy
Space-Based Astronomy
Spinoff technology
Many technologies that were originally developed for use in space programs are now used by people around the world. More than 1400 different NASA technologies, such as cordless tools, have been passed on to commercial industries for common use; these are called spinoffs.

23. Objectives Describe the history of lunar exploration.
Section 27.2
The Moon
Objectives
Describe the history of lunar exploration.
Recognize lunar properties and structures.
Identify features of the Moon.
Explain the theory of how the Moon formed.

24. Section 27.2
The Moon
The Moon, Earth’s nearest neighbor in space, is unique among the moons in our solar system.
Review Vocabulary
lava: magma that flows onto the surface from the interior of an astronomical body

25. New Vocabulary The Moon albedo highland maria impact crater ejecta ray
Section 27.2
The Moon
New Vocabulary
albedo
highland
maria
impact crater
ejecta
ray
rille
regolith

26. Section 27.2
The Moon
Exploring the Moon
Most knowledge of the Moon comes from explorations by space probes and from landings by astronauts.

27. Section 27.2
The Moon
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.

28. Section 27.2
The Moon
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.

29. Section 27.2
The Moon
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.
After a gap of many years, scientists hope to return to the Moon before 2029.

30. Section 27.2
The Moon
The Lunar Surface
The albedo of the Moon, the percentage of incoming sunlight that its surface reflects, is very small—only about 7 percent.
In contrast, Earth has an average albedo of nearly 31 percent.

31. Section 27.2
The Moon
The Lunar Surface
Lunar highlands are heavily cratered regions of the Moon that are light in color and mountainous.
Maria are dark, smooth plains, which average 3 km lower in elevation and have few craters.

32. The Lunar Surface Lunar craters
Section 27.2
The Moon
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.

33. The Lunar Surface Lunar craters
Section 27.2
The Moon
The Lunar Surface
Lunar craters
Some craters have long trails of ejecta, called rays, that radiate outward from the impact site.
Rilles are meandering, valleylike structures that might be collapsed lava tubes.

34. The Lunar Surface Lunar properties
Section 27.2
The Moon
The Lunar Surface
Lunar properties
Earth’s moon is unique among all the moons in the solar system.
1.It is one of the largest moons compared to the radius and mass of the planet it orbits.
2. It is a solid, rocky body, in contrast with the icy compositions of other moons of the solar system.

35. The Lunar Surface Lunar properties
Section 27.2
The Moon
The Lunar Surface
Lunar properties
3.The Moon’s orbit is farther from Earth relative to the distance of most moons from the planets they orbit.
4. Moon’s albedo is 7%. Earth’s 31%.

36. The Lunar Surface Lunar properties
Section 27.2
The Moon
The Lunar Surface
Lunar properties
5.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.

37. The Moon Please click the image above to view the interactive table.
Section 27.2
The Moon
Please click the image above to view the interactive table.

38. Section 27.2
The Moon
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.

39. History of the Moon Layered structure
Section 27.2
The Moon
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.

40. History of the Moon Formation of maria
Section 27.2
The Moon
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.

41. History of the Moon Tectonics
Section 27.2
The Moon
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.

42. Section 27.2
The 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.

43. Section 27.2
The Moon
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.

44. Section 27.1 Tools of Astronomy
Study Guide
Key Concepts
Section 27.1 Tools of Astronomy
Radiation emitted or reflected by distant objects allows scientists to study the universe.
Telescopes collect and focus electromagnetic radiation emitted or reflected from distant objects.
Electromagnetic radiation is classified by wavelength and frequency.

45. Section 27.1 Tools of Astronomy
Study Guide
Key Concepts
Section 27.1 Tools of Astronomy
The two main types of optical telescopes are refractors and reflectors.
Space-based astronomy includes the study of orbiting telescopes, satellites, and probes.
Technology originally developed to explore space is now used by people on Earth.

46. 27
Study Guide
Key Concepts
Section 27.2 The Moon
The Moon, Earth’s nearest neighbor in space, is unique among the moons in our solar system.
Astronomers have gathered information about the Moon using telescopes, space probes, and astronaut exploration.
Like Earth’s crust, the Moon’s crust is composed mostly of silicates.

47. 27
Study Guide
Key Concepts
Section 27.2 The Moon
Surface features on the Moon include highlands, maria, ejecta, rays, and rilles. It is heavily cratered.
The Moon probably formed about 4.5 bya in a collision between Earth and a Mars-size object.

48. 27 The Sun-Earth-Moon System
27.1 Section Questions
Gamma rays move through space at a greater speed than do radio waves.
a. true
b. false

49. 27 The Sun-Earth-Moon System
27.1 Section Questions
Which objects produce the image in a refracting telescope?
a. mirrors
b. lamps
c. lenses
d. prisms

50. 27 The Sun-Earth-Moon System
27.1 Section Questions
What advantage do telescopes in space have over similar instruments on Earth’s surface?
a. The telescopes are closer to the object.
b. The telescopes are above the atmosphere.
c. The telescopes are safe from damage.
d. The telescopes are always in the dark.

51. 27 The Sun-Earth-Moon System
27.2 Section Questions
The Moon has a lower density than that of Earth.
a. true
b. false

52. 27 The Sun-Earth-Moon System
27.2 Section Questions
Which term refers to valleylike structures on the Moon that might be lava tubes?
a. ejecta
b. rays
c. rilles
d. highlands

53. 27 The Sun-Earth-Moon System
27.2 Section Questions
Which theory about how the Moon formed is most accepted?
a. The Moon was captured by Earth.
b. The Moon condensed with Earth.
c. A Mars-sized object struck Earth.
d. A piece broke off of Earth.