Our Earth & Moon
(Chapter 16)
Student Learning Objectives
• Compare and contrast interior structures of the
Earth & Moon
• Describe surface features for our Earth & Moon
• State the theory for the origin of our moon.
What do we know about the Earth?
Earth is a relatively small
planet.
Oblate spheroid
71% liquid water surface
The Earth is an active
terrestrial planet.
7 main tectonic plates
Question: What is Pangea?
Fun Earth Facts
• Travels through space at 660,000 miles per hour
• Weighs 6,588,000,000,000,000,000,000,000 tons
• Rotates more slowly in March than in September
• Rotates at an average speed of 283 mph
If the oceans were evenly distributed over the
entire surface of the Earth, the water would be
approximately 2 miles deep at every point
Planet Albedo
Earth reflects an average of 30% of the sunlight
that is incident upon the surface.
Earth Albedo= 0.306
Venus Albedo = 0.750
Planet Earth is composed primarily of metals.
Fe, O, Si, Mg
Earth is in the “Habitable Zone” (–60º F to +120º F)
Practice: What does it mean for a
planet to be in the habitable zone?
Atmosphere
76% Nitrogen (N2)
22% Oxygen (O2)
2% Trace Gasses
The greenhouse effect
traps heat near the
surface of Earth.
Global warming is the
general increase in
planet temperatures.
Question: Is the greenhouse effect “bad”?
Practice
1) What contributes most to our greenhouse
effect?
2) What common molecule increases albedo?
3) What is ozone and why is it important?
Earth’s Magnetic Field
The Earth is surrounded by a magnetic field, and the
poles switch!
http://www.nasa.gov/topics/earth/features/2012-poleReversal.html
The motion of ionized
particles inside Earth's
liquid core coupled
with Earth’s rotation
induces the magnetic
field.
Solar particles interact with Earth's magnetic field.
What causes the Aurora?
Solar particles hit
air molecules
Air molecules
are “excited”
Molecules give off light
(return to Ground state)
How do we know the interior structure of the Earth?
Earthquake waves allow
mapping of interior.
 P waves travel through both
solid and liquid matter
 S waves travel through only
solid matter
 P waves are compression
waves. (Pressure Wave)
Longitudinal wave
 S waves begin as a quick
vibration. (Shear Wave)
Transverse wave
Earth’s 5 Layers
Solid inner core
(iron and nickel)
Liquid Outer Core
(convection currents)
Molten Mantle
&
Constantly changing surface
(solid rock flows)
Earth’s Changing Outer Layers
Crust
(plates floating on mantle)
Surface
(shifting plates & weather result in continual change)
What are the characteristics of the Moon?
 The Moon is about 25,000
miles more distant at
apogee than at perigee.
Harvest Moon
It would take an average of 135
days to drive to the moon at a
speed of 70 mph
Image Credit: APOD
Fun Moon Facts
• Earth-Moon distance is an
average of 239,000 miles
or 0.00257 AU
• More than 100 spacecraft
have been launched to
explore the moon
• If the Sun were as tall as a
typical front door
– Earth would be the size of
a nickel
– The Moon would be the
size of a pea
The moon is a satellite of the Earth.
49 Moons would fit across the diameter of the Earth
About Our Moon
 Cool and Solid
 3 Surface features
1/4 size of Earth
-387 to 253 °F
Regolith
Highlands
Maria (craters filled with basalt)
The moon is egg shaped with the large end
pointed towards earth.
Practice
1) Why is the temperature range larger on the
Moon than it is on Earth?
2) Compare the interior layers of the Earth and
Moon. Are they relatively similar or very
different?
The Apollo Missions were 1963 – 1972.
July 20, 1969
Neil Armstrong steps on Moon
Followed by Edwin Aldrin
Apollo 11 Mission
Giant Impact Theory
Earth was impacted by a Mars-size object after Earth
had differentiated.
Earth tilt
Moon composition