chapter 5 earth and its moon

Copyright © 2010 Pearson Education, Inc.Copyright © 2010 Pearson Education, Inc.

Chapter 5 Earth and Its

Moon

Copyright © 2010 Pearson Education, Inc.

Chapter 5Earth and Its Moon


Tatoonie


Units of Chapter 5Earth and the Moon in BulkThe TidesAtmospheresInteriorsSurface Activity on EarthThe Surface of the MoonMagnetospheresHistory of the Earth–Moon System

a) an atmosphere.b) a hydrosphere.c) a magnetosphere.d) It lacks all of the above.

Question 1

The Moon’s internal structure is similar to Earth’s, but the Moon lacks

a) an atmosphere.b) a hydrosphere.c) a magnetosphere.d) It lacks all of the above.

Question 1

The Moon’s internal structure is similar to Earth’s, but the Moon lacks

Both the Earth and Moon have a core, mantle, and crust, but the Earth has a liquid water-rich layer, air, and a magnetic field.


Earth and the Moon in Bulk


Tides are due to gravitational force on Earth from Moon – force on near side of Earth is greater than force on far side. Water can flow freely in response.

The Tides


The Sun has less effect, but it does modify the lunar tides.

The Tides

At what lunar phase would the variation between high & low tides be greatest?

Question 2a) new moonb) waxing crescent moonc) full moond) third quarter moone) both new and full moon

At what lunar phase would the variation between high & low tides be greatest?

Question 2a) new moonb) waxing crescent moonc) full moond) third quarter moone) both new and full moon

At new and full moon phases, the Sun and Moon

combine to stretch the Earth and its oceans even more.

We see higher high tides and lower low tides.


Tides tend to exert a “drag” force on Earth, slowing its rotation.This will continue until Earth rotates synchronously with the Moon, so that the same side of Earth always points toward the Moon.

The Tides


The TidesThis has already happened with the Moon, whose near side is always toward Earth.

Question 3

a) the Sun’s gravityb) Earth’s magnetic field c) Earth’s tidal forced) the solar winde) the Moon’s magnetic field

What force riveted the Moon’s near side to constantly face Earth?

Question 3

a) the Sun’s gravityb) Earth’s magnetic field c) Earth’s tidal forced) the solar winde) the Moon’s magnetic field

What force rivets the Moon’s near side to constantly face Earth?

Just as the Moon creates tides on Earth with its gravitational

force, the Earth affects the Moon, too.

Because of Earth’s tidal force, the Moon spins once a month.


• The blue curve shows the temperature at each altitude.

• Troposphere is where convection takes place – responsible for weather.

Atmospheres


Convection depends on warming of ground by the Sun.

Atmospheres


Ionosphere is ionized by solar radiation, and is a good conductor.Reflects radio waves in the AM range, but transparent to FM and TV.Ozone layer is in the stratosphere and absorbs ultraviolet radiation.

Atmospheres


Chlorofluorocarbons (CFCs) have been damaging the ozone layer, resulting in ozone hole. 1 chlorine atom can destroy up to a 100,000 ozone molecules. It will be decades before the hole will go away.

Earth’s Growing Ozone Hole

Question 4

A planetary atmosphere with ozone could protect surface dwellers from

a) ultraviolet radiation.b) charged particles in the solar wind.c) meteor impacts.d) optical radiation.e) radar waves.

Question 4

A planetary atmosphere with ozone could protect surface dwellers from

a) ultraviolet radiation.b) charged particles in the solar wind.c) meteor impacts.d) optical radiation.e) radar waves.

Ozone in the stratosphere (about 30-50 km high)

absorbs UV light, and heats the upper atmosphere.


Surface heating:• Sunlight that is not reflected is

absorbed by Earth’s surface, warming it.

• Surface re-radiates as infrared thermal radiation.

• Atmosphere absorbs some infrared, causing further heating.

Atmospheres


This is known as the greenhouse effect.

Atmospheres

The principal greenhouse gases in our present atmosphere are

Question 5a) hydrogen and helium.b) oxygen and nitrogen.c) water vapor and carbon dioxide.d) methane and ammonia.e) sulfuric acid vapor and CO2.

Question 5a) hydrogen and helium.b) oxygen and nitrogen.c) water vapor and carbon dioxide.d) methane and ammonia.e) sulfuric acid vapor and CO2.

The principal greenhouse gases in our present atmosphere are

A greenhouse gas lets shorter- wavelength light pass through, but absorbs longer-wavelength light.


The Greenhouse Effect and Global Warming

There is extremely strong evidence that Earth is getting warmer. The cause of this warming is a subject of intense debate; many scientists believe it is related to the corresponding increase in atmospheric carbon dioxide.

Greenhouse Effect

• Some greenhouse gas is necessary. Without a trace of GHG Earth would be -19 C instead of +14 C.

• Too much GHG and Earth gets too hot.• GHG such as water vapor, CO2 and

Methane.

Without the greenhouse effect in our atmosphere

Question 6

a) we would not have to worry about ecological problems.

b) the Earth’s oceans would be frozen.c) the amount of nitrogen & oxygen

would be much less.d) the icecaps would have melted.e) global warming would still occur.

Without the greenhouse effect in our atmosphere

Question 6

a) we would not have to worry about ecological problems.

b) the Earth’s oceans would be frozen.c) the amount of nitrogen & oxygen

would be much less.d) the icecaps would have melted.e) global warming would still occur.

Earth’s greenhouse effect makes the planet about 40° C hotter than it would otherwise be.

This raises the average surface temperature above the freezing point of water.


Seismic waves:• Earthquakes produce both pressure and

shear waves. • Pressure waves will travel through both

liquids and solids.• Shear waves will not travel through liquids,

as liquids do not resist shear forces.• Wave speed depends on density of material.

Interiors


InteriorsThe pressure wave is a longitudinal wave, whereas the shear wave is a transverse wave. A shear wave cannot propagate within a liquid.


P - wave


S - Wave


Can use pattern of reflections during earthquakes to deduce interior structure of Earth.

Interiors


Currently accepted model

Interiors


Mantle is much less dense than core.Mantle is rocky; core is metallic, consisting of iron and nickel.Outer core is liquid; inner core is solid, due to pressure.Volcanic lava comes from mantle, allows analysis of composition.

Interiors


Continental drift: Earth’s entire surface is covered with crustal plates, which can move independently.At plate boundaries, earthquakes and volcanoes can occur.

Surface Activity on Earth

Volcanoearthquake

Plate line

DriftDirection


San Andreas Fault2 inches per year

21 feet in 1906 quake


Plates moving away from each other create rifts.

Surface Activity on Earth


If we follow the continental drift backward, the continents merge into one, called Pangaea.

5.5 Surface Activity on Earth


The Moon has large dark flat areas, due to lava flow, called maria (early observers thought they were oceans).

The Surface of the Moon


The far side of the Moon is relatively unmarked.


Question 7

Lunar maria are found

a) uniformly all over the Moon.b) mostly on the side facing Earth.c) mostly on the far side of the Moon.d) only in the dark areas, out of sunlight.e) in the highlands, among mountains.

Question 7

Lunar maria are found

a) uniformly all over the Moon.b) mostly on the side facing Earth.c) mostly on the far side of the Moon.d) only in the dark areas, out of sunlight.e) in the highlands, among mountains.

Because the Moon keeps its near side always facing Earth, that side has a thinner crust, and is also less

cratered.


Crater formation: Meteoroid strikes the Moon, ejecting material; explosion ejects more material, leaving a crater.



• Craters are typically about 10 times as wide as the meteoroid creating them, and twice as deep.

• Rock is pulverized to a much greater depth.• Most lunar craters date to at least 3.9 billion

years ago; much less bombardment since then.



Very large and very small lunar craters



The Surface of the MoonRegolith: Thick layer of dust left by meteorite impacts

The Moon is still being bombarded, especially by very small “micrometeoroids”; softens features.


MagnetospheresThe magnetosphere is the region around Earth where charged particles from the solar wind are trapped.


MagnetospheresThese charged particles are trapped in areas called the Van Allen belts, where they spiral around the magnetic field lines.

The region around Earth where the magnetic field traps charged particles is the

Question 8

a) ozone layer.b) exosphere.c) Van Allen radiation belts.d) corona.e) aurora borealis and australis.

The region around Earth where the magnetic field traps charged particles is the

Question 8

a) ozone layer.b) exosphere.c) Van Allen radiation belts.d) corona.e) aurora borealis and australis.

The Earth’s magnetosphere influences the charged

particles of the solar wind.

Some particles are channeled toward the poles,

creating the aurora.


MagnetospheresNear the poles, the Van Allen belts intersect the atmosphere. The charged particles can escape; when they do, they create glowing light called an aurora.

Question 9

Which of these is NOT a result of the Earth’s magnetic field?

a) a compass pointing northb) auroraec) the Van Allen radiation beltsd) volcanic eruptionse) the comet-like tail of charged

particles that extends past our Moon

Question 9

Which of these is NOT a result of the Earth’s magnetic field?

a) a compass pointing northb) auroraec) the Van Allen radiation beltsd) volcanic eruptionse) the comet-like tail of charged

particles that extends past our Moon

Our planet’s magnetosphere is generated by the

Earth’s rotation and its liquid metal core.

In contrast, the Moon doesn’t have a magnetic field.


Current theory of the Moon’s origin: glancing impact of Mars-sized body on the still-liquid Earth caused enough material, mostly from the mantle, to be ejected to form the Moon.Computer model

History of the Earth–Moon System


History of the Earth–Moon SystemFour billion years ago, the Moon had many craters but no maria. By three billion years ago, the maria had formed. Now, they also are covered with craters.

Question 10

Today, which of these theories best explains the Moon’s origin?

a) The fission theoryb) The giant impact theoryc) The capture theoryd) The co-formation theorye) The fusion theory

Question 10

Today, which of these theories best explains the Moon’s origin?

a) The fission theoryb) The giant impact theoryc) The capture theoryd) The co-formation theorye) The fusion theory

The giant impact theory seems to explain why the Moon is similar to Earth’s mantle, and why it doesn’t have a dense core.

Giant Impact Theory

chapter 5 earth and its moon

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