1. The Moon: Earth’s Fellow Traveler

2. Warm Up Questions CPS Questions (1-2)
Chapter 2, Lesson 2

3. Lesson Overview The Moon’s size and distance from Earth
The relationships between the Moon and the Earth
The Moon’s origins and surface
Chapter 2, Lesson 2

4. (Note to teacher: Use “Pick a Student” button in CPS)
Quick Write
If you had been one of the Apollo 11 astronauts, what about the Moon would you have been most curious to see or experience for yourself?
(Note to teacher: Use “Pick a Student” button in CPS)
Chapter 2, Lesson 2

5. The Distance from the Earth to the Moon
Ptolemy calculated the distance at 27.3 Earth diameters
Today we know Earth’s diameter is 12,800 kilometers, or 8,000 miles
The Moon is about 380,000 kilometers (240,000 miles) from Earth
Chapter 2, Lesson 2

6. How the Moon’s Size is Estimated
An object’s angular size is the angle between two lines that start at the observer and go to opposite sides of the object
Scientists can use the Moon’s angular size plus the distance from the Earth to the Moon, to calculate the diameter of the Moon
Chapter 2, Lesson 2

7. Why the Moon Appears to Be Larger at Certain Times
Moon appears to be larger at some times than others because its distance from Earth varies
Chapter 2, Lesson 2
Reprinted by permission of Creators Syndicate and John L. Hart FLP

8. Why the Moon Appears to Be Larger at Certain Times, cont.
Its orbit is elliptical
The Moon appears to be larger when it is at its perigee, or closest distance from the Earth
It appears smaller when at its apogee, or farthest distance from the Earth
Chapter 2, Lesson 2
Courtesy of Galileo Project , NASA

9. The Relationship Between the Moon and the Earth
A tidal force is a gravitation force that varies in strength and/or direction over an object and causes it to deform
Moon’s gravity pulls harder on those parts of Earth closer to it than on parts farther away
Chapter 2, Lesson 2

10. The Relationship Between the Moon and the Earth, cont.
Spring tides - exceptionally high and low tides that occur at the time of the new moon or the full moon, when the Sun, Moon and Earth are approximately aligned
Neap tides are the tides that occur when the difference between high and low tides is least
Chapter 2, Lesson 2

11. The Relationship Between the Moon and the Earth, cont.
Chapter 2, Lesson 2

12. Moon’s Rotation and Revolution
In times past, the Moon must have gone through a rotation period different from its revolution
Tidal friction – the friction that results from tides on a rotating object – has slowed the Moon down
The Earth and the Sun cause tides on the Moon
Tidal friction is at work on the Earth as well
Chapter 2, Lesson 2

13. How the Moon’s Location Influences the Earth’s “Wobble”
Precession - the conical shifting of the axis of a rotating object
The force acting on Earth to change its spin is gravity
The precession of the Earth means that eventually there will be a new “North Star”
Chapter 2, Lesson 2

14. The Moon’s Origin and Surface
The moonscape has two principal features:
The maria or “seas” – lunar lowlands that resemble seas when viewed from Earth
The crated mountainous regions
Chapter 2, Lesson 2
Courtesy of NASA

15. The Moon’s Origin and Surface, cont.
Craters are the result of the impact of meteorites – interplanetary chunks of stone or matter that have crashed into a planet or moon from space
Volcanic eruptions did produce the maria
Impacts from large asteroids formed the craters
Dark lava flooded the basins of the craters to form the maria
Chapter 2, Lesson 2

16. Features of the Moon’s Crust
Moon’s crust ranges from about 60 kilometers to 100 kilometers deep
Lunar mountains are the result of millions of ancient craters piled up on top of one another
Chapter 2, Lesson 2

17. Four Theories of the Moon’s Origins
Double Planet Theory - the Moon was formed at the same time as the Earth
Fission Theory - the Moon formed from material spun off from the Earth
Capture Theory - the Moon is made up of Solar System debris captured by Earth
Chapter 2, Lesson 2

18. Four Theories of the Moon’s Origins, cont.
Large Impact Theory
Moon formed as the result of an impact between a large (Mars-sized) object and the Earth
The metal cores of the two bodies combined to form the massive core of Earth
The lighter material became the Moon
Chapter 2, Lesson 2

19. Learning Check CPS Questions (3-4)
Chapter 2, Lesson 2

20. Activity 1: The Moon: Earth’s Fellow Traveler Review Challenge
Use your textbook to identify the terms and people to complete the worksheet
Chapter 2, Lesson 2

21. Activity 2: The Moon’s Origin
The text presents four different theories of the Moon’s origin. As a group, review pages in the textbook and complete the chart.
Then answer the reflection questions on your own.
Chapter 2, Lesson 2

22. Activity 3: Just How Far?
Work together to solve the math problems about distance
Be prepared to share your answers
Chapter 2, Lesson 2

23. Technology Enrichment: Tides & the Moon
Visit the website link listed on your worksheet and follow the step by step directions.
 Answer the questions and be prepared to share your findings.
Chapter 2, Lesson 2

24. Review
Through time, we have become more exact in our measurements of the Moon and how far away it is
The Moon, the Earth and the Sun all have gravitational influences on one another
The Moon’s mountains formed differently from Earth’s
Chapter 2, Lesson 2

25. Review, cont.
The moonscape has two principal features: the maria and the cratered mountainous regions
There are four theories of the Moon’s origins:
Double planet theory
Fission theory
Capture theory
Large impact theory
Chapter 2, Lesson 2

26. Review Questions CPS Questions (5-6)
Chapter 2, Lesson 2

27. Summary The Moon’s size and distance from Earth
The relationships between the Moon and the Earth
The Moon’s origin and surface
Chapter 2, Lesson 2

28. Next… Done – The Moon: Earth’s Fellow Traveler
Next – The Sun and Its Domain
Chapter 2, Lesson 2
Courtesy of SOHO-EIT Consortium/ESA/NASA.