The Moon: Earth’s Fellow Traveler

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

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

(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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Activity 2: The Moon’s Origin The text presents four different theories of the Moon’s origin. As a group, review pages 70-71 in the textbook and complete the chart. Then answer the reflection questions on your own. Chapter 2, Lesson 2

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

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

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

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

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

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

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.