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Copyright © 2012 Pearson Education, Inc. Chapter 7 Earth and the Terrestrial Worlds Insert ECP6 Chapter 7 Opener.

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Presentation on theme: "Copyright © 2012 Pearson Education, Inc. Chapter 7 Earth and the Terrestrial Worlds Insert ECP6 Chapter 7 Opener."— Presentation transcript:

1 Copyright © 2012 Pearson Education, Inc. Chapter 7 Earth and the Terrestrial Worlds Insert ECP6 Chapter 7 Opener

2 Copyright © 2012 Pearson Education, Inc. Mercury Craters Smooth plains Cliffs

3 Copyright © 2012 Pearson Education, Inc. Venus Volcanoes Few craters Radar view of a twin- peaked volcano

4 Copyright © 2012 Pearson Education, Inc. Mars Some craters Volcanoes Riverbeds? Insert ECP6 Figure 7.26

5 Copyright © 2012 Pearson Education, Inc. Moon Craters Smooth plains

6 Copyright © 2012 Pearson Education, Inc. Earth Volcanoes Craters Mountains Riverbeds

7 Copyright © 2012 Pearson Education, Inc. Why have the planets turned out so differently, even though they formed at the same time from the same materials?

8 Copyright © 2012 Pearson Education, Inc. 9.1 Earth as a Planet Our goals for learning: Why is Earth geologically active? What processes shape Earths surface? How does Earths atmosphere affect the planet?

9 Copyright © 2012 Pearson Education, Inc. Why is Earth geologically active?

10 Copyright © 2012 Pearson Education, Inc. Earths Interior Core: Highest density; nickel and iron Mantle: Moderate density; silicon, oxygen, etc. Crust: Lowest density; granite, basalt, etc.

11 Copyright © 2012 Pearson Education, Inc. Terrestrial Planet Interiors Applying what we have learned about Earths interior to other planets tells us what their interiors are probably like.

12 Copyright © 2012 Pearson Education, Inc. Why do water and oil separate? A.Water molecules repel oil molecules electrically. B.Water is denser than oil, so oil floats on water. C.Oil is more slippery than water, so it slides to the surface of the water. D.Oil molecules are bigger than the spaces between water molecules.

13 Copyright © 2012 Pearson Education, Inc. Why do water and oil separate? A.Water molecules repel oil molecules electrically. B.Water is denser than oil, so oil floats on water. C.Oil is more slippery than water, so it slides to the surface of the water. D.Oil molecules are bigger than the spaces between water molecules.

14 Copyright © 2012 Pearson Education, Inc. Differentiation Gravity pulls high-density material to center. Lower-density material rises to surface. Material ends up separated by density.

15 Copyright © 2012 Pearson Education, Inc. Thought Question What is necessary for differentiation to occur in a planet? A.It must have metal and rock in it. B.It must be a mix of materials of different density. C.Material inside must be able to flow. D.All of the above E.B and C

16 Copyright © 2012 Pearson Education, Inc. Thought Question What is necessary for differentiation to occur in a planet? A.It must have metal and rock in it. B.It must be a mix of materials of different density. C.Material inside must be able to flow. D.All of the above E.B and C

17 Copyright © 2012 Pearson Education, Inc. Lithosphere A planets outer layer of cool, rigid rock is called the lithosphere. It floats on the warmer, softer rock that lies beneath.

18 Copyright © 2012 Pearson Education, Inc. Thought Question Do rocks s-t-r-e-t-c-h? A.No. Rock is rigid and cannot deform without breaking. B.Yes, but only if it is molten rock. C.Yes. Rock under strain may slowly deform.

19 Copyright © 2012 Pearson Education, Inc. Thought Question Do rocks s-t-r-e-t-c-h? A.No. Rock is rigid and cannot deform without breaking. B.Yes, but only if it is molten rock. C.Yes. Rock under strain may slowly deform.

20 Copyright © 2012 Pearson Education, Inc. Strength of Rock Rock stretches when pulled slowly but breaks when pulled rapidly. The gravity of a large world pulls slowly on its rocky content, shaping the world into a sphere.

21 Copyright © 2012 Pearson Education, Inc. Heat Drives Geological Activity Convection: Hot rock rises, cool rock falls. One convection cycle takes 100 million years on Earth.

22 Copyright © 2012 Pearson Education, Inc. Sources of Internal Heat 1.Gravitational potential energy of accreting planetesimals 2.Differentiation 3.Radioactivity

23 Copyright © 2012 Pearson Education, Inc. Heating of Interior over Time Accretion and differentiation when planets were young Radioactive decay is most important heat source today.

24 Copyright © 2012 Pearson Education, Inc. Cooling of Interior Convection transports heat as hot material rises and cool material falls. Conduction transfers heat from hot material to cool material. Radiation sends energy into space.

25 Copyright © 2012 Pearson Education, Inc. Thought Question What cools off faster? A.A grande-size cup of Starbucks coffee B.A teaspoon of cappuccino in the same cup

26 Copyright © 2012 Pearson Education, Inc. Thought Question What cools off faster? A.A grande-size cup of Starbucks coffee B.A teaspoon of cappuccino in the same cup

27 Copyright © 2012 Pearson Education, Inc. Thought Question What cools off faster? A.A big terrestrial planet B.A tiny terrestrial planet

28 Copyright © 2012 Pearson Education, Inc. Thought Question What cools off faster? A.A big terrestrial planet B.A tiny terrestrial planet

29 Copyright © 2012 Pearson Education, Inc. Role of Size Smaller worlds cool off faster and harden earlier. The Moon and Mercury are now geologically dead.

30 Copyright © 2012 Pearson Education, Inc. Surface Area-to-Volume Ratio Heat content depends on volume. Loss of heat through radiation depends on surface area. Time to cool depends on surface area divided by volume: Larger objects have a smaller ratio and cool more slowly.

31 Copyright © 2012 Pearson Education, Inc. Planetary Magnetic Fields Moving charged particles create magnetic fields. A planets interior can create magnetic fields if its core is electrically conducting, convecting, and rotating.

32 Copyright © 2012 Pearson Education, Inc. Earths Magnetosphere Earths magnetic field protects us from charged particles from the Sun. The charged particles can create aurorae (Northern lights).

33 Copyright © 2012 Pearson Education, Inc. Thought Question If the planet core is cold, do you expect it to have magnetic fields? A.Yes. Refrigerator magnets are cold, and they have magnetic fields. B.No. Planetary magnetic fields are generated by moving charges around, and if the core is cold, nothing is moving.

34 Copyright © 2012 Pearson Education, Inc. Thought Question If the planet core is cold, do you expect it to have magnetic fields? A.Yes. Refrigerator magnets are cold, and they have magnetic fields. B.No. Planetary magnetic fields are generated by moving charges around, and if the core is cold, nothing is moving.

35 Copyright © 2012 Pearson Education, Inc. Special Topic: How do we know whats inside a planet? P waves push matter back and forth. S waves shake matter side to side.

36 Copyright © 2012 Pearson Education, Inc. Special Topic: How do we know whats inside a planet? P waves go through Earths core, but S waves do not. We conclude that Earths core must have a liquid outer layer.

37 Copyright © 2012 Pearson Education, Inc. What processes shape Earths surface?

38 Copyright © 2012 Pearson Education, Inc. Geological Processes Impact cratering Impacts by asteroids or comets Volcanism Eruption of molten rock onto surface Tectonics Disruption of a planets surface by internal stresses Erosion Surface changes made by wind, water, or ice

39 Copyright © 2012 Pearson Education, Inc. Impact Cratering Most cratering happened soon after the solar system formed. Craters are about 10 times wider than the objects that made them. Small craters greatly outnumber large ones.

40 Copyright © 2012 Pearson Education, Inc. Impact Craters Meteor Crater (Arizona) Tycho (Moon)

41 Copyright © 2012 Pearson Education, Inc. Volcanism Volcanism happens when molten rock (magma) finds a path through lithosphere to the surface. Molten rock is called lava after it reaches the surface.

42 Copyright © 2012 Pearson Education, Inc. Outgassing Volcanism also releases gases from Earths interior into the atmosphere.

43 Copyright © 2012 Pearson Education, Inc. Tectonics Convection of the mantle creates stresses in the crust called tectonic forces. Compression forces make mountain ranges. A valley can form where the crust is pulled apart.

44 Copyright © 2012 Pearson Education, Inc. Plate Tectonics on Earth Earths continents slide around on separate plates of crust. Plate Tectonics on Earth

45 Copyright © 2012 Pearson Education, Inc. Erosion Erosion is a blanket term for weather-driven processes that break down or transport rock. Processes that cause erosion include Glaciers Rivers Wind

46 Copyright © 2012 Pearson Education, Inc. Erosion by Water The Colorado River continues to carve the Grand Canyon.

47 Copyright © 2012 Pearson Education, Inc. Erosion by Ice Glaciers carved the Yosemite Valley.

48 Copyright © 2012 Pearson Education, Inc. Erosion by Wind Wind wears away rock and builds up sand dunes.

49 Copyright © 2012 Pearson Education, Inc. Erosional Debris Erosion can create new features by depositing debris.

50 Copyright © 2012 Pearson Education, Inc. How does Earths atmosphere affect the planet?

51 Copyright © 2012 Pearson Education, Inc. Effects of Atmosphere on Earth 1.Erosion 2.Radiation protection 3.Greenhouse effect 4.Makes the sky blue!

52 Copyright © 2012 Pearson Education, Inc. Radiation Protection All X-ray light is absorbed very high in the atmosphere. Ultraviolet light is absorbed by ozone (O 3 ).

53 Copyright © 2012 Pearson Education, Inc. The Greenhouse Effect

54 Copyright © 2012 Pearson Education, Inc. Earths atmosphere absorbs light at most wavelengths.

55 Copyright © 2012 Pearson Education, Inc. Greenhouse effect: Certain molecules let sunlight through but trap escaping infrared photons. (H 2 O, CO 2, CH 4 ) The Greenhouse Effect

56 Copyright © 2012 Pearson Education, Inc. A Greenhouse Gas Any gas that absorbs infrared Greenhouse gas: molecules with two different types of elements (CO 2, H 2 O, CH 4 ) Not a greenhouse gas: molecules with one or two atoms of the same element (O 2, N 2 )

57 Copyright © 2012 Pearson Education, Inc. Greenhouse Effect: Bad? Because of the greenhouse effect, Earth is much warmer than it would be without an atmosphere…but so is Venus.

58 Copyright © 2012 Pearson Education, Inc. Thought Question Why is the sky blue? A.The sky reflects light from the oceans. B.Oxygen atoms are blue. C.Nitrogen atoms are blue. D.Air molecules scatter blue light more than red light. E.Air molecules absorb red light.

59 Copyright © 2012 Pearson Education, Inc. Thought Question Why is the sky blue? A.The sky reflects light from the oceans. B.Oxygen atoms are blue. C.Nitrogen atoms are blue. D.Air molecules scatter blue light more than red light. E.Air molecules absorb red light.

60 Copyright © 2012 Pearson Education, Inc. Why the sky is blue Atmosphere scatters blue light from the Sun, making it appear to come from different directions. Sunsets are red because less of the red light from the Sun is scattered.

61 Copyright © 2012 Pearson Education, Inc. What have we learned? Why is Earth geologically active? Earth retains plenty of internal heat because it is large for a terrestrial planet. That heat drives geological activity, keeping the core molten and driving geological activity. The circulation of molten metal in the core generates Earths magnetic field.

62 Copyright © 2012 Pearson Education, Inc. What have we learned? What geological processes shape Earths surface? Impact cratering, volcanism, tectonics, and erosion How does Earths atmosphere affect the planet? Erosion Protection from radiation Greenhouse effect

63 Copyright © 2012 Pearson Education, Inc. 7.2 Mercury and the Moon: Geologically Dead Our goals for learning: Was there ever geological activity on the Moon or Mercury?

64 Copyright © 2012 Pearson Education, Inc. Was there ever geological activity on the Moon or Mercury?

65 Copyright © 2012 Pearson Education, Inc. Moon Some volcanic activity 3 billion years ago must have flooded lunar craters, creating lunar maria. The Moon is now geologically dead.

66 Copyright © 2012 Pearson Education, Inc. Cratering of Mercury Mercury has a mixture of heavily cratered and smooth regions like the Moon. The smooth regions are likely ancient lava flows.

67 Copyright © 2012 Pearson Education, Inc. Cratering of Mercury The Caloris Basin is the largest impact crater on Mercury. Region opposite the Caloris Basin is jumbled from seismic energy of impact.

68 Copyright © 2012 Pearson Education, Inc. Tectonics on Mercury Long cliffs indicate that Mercury shrank early in its history.

69 Copyright © 2012 Pearson Education, Inc. What have we learned? Was there ever geological activity on the Moon or Mercury? Early cratering on the Moon and Mercury is still present, indicating that activity ceased long ago. Lunar maria resulted from early volcanism. Tectonic features on Mercury indicate early shrinkage.

70 Copyright © 2012 Pearson Education, Inc. 7.3 Mars: A Victim of Planetary Freeze-Drying Our goals for learning: What geological features tell us that water once flowed on Mars? Why did Mars change?

71 Copyright © 2012 Pearson Education, Inc. Mars versus Earth 50% Earths radius, 10% Earths mass 1.5 AU from the Sun Axis tilt about the same as Earth Similar rotation period Thin CO 2 atmosphere: little greenhouse Main difference: Mars is SMALLER

72 Copyright © 2012 Pearson Education, Inc. Seasons on Mars Seasons on Mars are more extreme in the southern hemisphere because of its elliptical orbit.

73 Copyright © 2012 Pearson Education, Inc. Storms on Mars Seasonal winds on Mars can drive huge dust storms.

74 Copyright © 2012 Pearson Education, Inc. What geological features tell us that water once flowed on Mars?

75 Copyright © 2012 Pearson Education, Inc. The surface of Mars appears to have ancient riverbeds.

76 Copyright © 2012 Pearson Education, Inc. The condition of craters indicates surface history. Eroded crater

77 Copyright © 2012 Pearson Education, Inc.

78 Volcanoes…as recent as 180 million years ago…

79 Copyright © 2012 Pearson Education, Inc. Past tectonic activity…

80 Copyright © 2012 Pearson Education, Inc. Opportunity Spirit

81 Copyright © 2012 Pearson Education, Inc Opportunity rover provided strong evidence for abundant liquid water on Mars in the distant past. How could Mars have been warmer and wetter in the past?

82 Copyright © 2012 Pearson Education, Inc. Today, most water lies frozen underground (blue regions). Some scientists believe accumulated snowpack melts carve gullies even today.

83 Copyright © 2012 Pearson Education, Inc. Why did Mars change?

84 Copyright © 2012 Pearson Education, Inc. Climate Change on Mars Mars has not had widespread surface water for 3 billion years. The greenhouse effect probably kept the surface warmer before that. Somehow Mars lost most of its atmosphere.

85 Copyright © 2012 Pearson Education, Inc. Climate Change on Mars Magnetic field may have preserved early Martian atmosphere. Solar wind may have stripped atmosphere after field decreased because of interior cooling.

86 Copyright © 2012 Pearson Education, Inc. What have we learned? What geological features tell us that water once flowed on Mars? Dry riverbeds, eroded craters, and rock-strewn floodplains all show that water once flowed on Mars. Mars today has ice, underground water ice, and perhaps pockets of underground liquid water. Why did Mars change? Marss atmosphere must have once been much thicker for its greenhouse effect to allow liquid water on the surface. Somehow Mars lost most of its atmosphere, perhaps because of a declining magnetic field.

87 Copyright © 2012 Pearson Education, Inc. 7.4 Venus: A Hothouse World Our goals for learning: Is Venus geologically active? Why is Venus so hot?

88 Copyright © 2012 Pearson Education, Inc. Is Venus geologically active?

89 Copyright © 2012 Pearson Education, Inc. Cratering on Venus Impact craters, but fewer than Moon, Mercury, Mars

90 Copyright © 2012 Pearson Education, Inc. Volcanoes on Venus Many volcanoes

91 Copyright © 2012 Pearson Education, Inc. Tectonics on Venus Fractured and contorted surface indicates tectonic stresses

92 Copyright © 2012 Pearson Education, Inc. Erosion on Venus Photos of rocks taken by lander show little erosion

93 Copyright © 2012 Pearson Education, Inc. Does Venus have plate tectonics? Most of Earths major geological features can be attributed to plate tectonics, which gradually remakes Earths surface. Venus does not appear to have plate tectonics, but its entire surface seems to have been repaved 750 million years ago.

94 Copyright © 2012 Pearson Education, Inc. Why is Venus so hot?

95 Copyright © 2012 Pearson Education, Inc. Why is Venus so hot? The greenhouse effect on Venus keeps its surface temperature at 470°C. But why is the greenhouse effect on Venus so much stronger than on Earth?

96 Copyright © 2012 Pearson Education, Inc. Atmosphere of Venus Venus has a very thick carbon dioxide atmosphere with a surface pressure 90 times that of Earth.

97 Copyright © 2012 Pearson Education, Inc. Greenhouse Effect on Venus Thick carbon dioxide atmosphere produces an extremely strong greenhouse effect. Earth escapes this fate because most of its carbon and water are in rocks and oceans.

98 Copyright © 2012 Pearson Education, Inc. Atmosphere of Venus Reflective clouds contain droplets of sulfuric acid. The upper atmosphere has fast winds that remain unexplained.

99 Copyright © 2012 Pearson Education, Inc. Runaway Greenhouse Effect The runaway greenhouse effect would account for why Venus has so little water. Greater heat, more evaporation More evaporation, stronger greenhouse effect

100 Copyright © 2012 Pearson Education, Inc. Thought Question What is the main reason Venus is hotter than Earth? A.Venus is closer to the Sun than Earth. B.Venus is more reflective than Earth. C.Venus is less reflective than Earth. D.The greenhouse effect is much stronger on Venus than on Earth. E.Human activity has led to declining temperatures on Earth.

101 Copyright © 2012 Pearson Education, Inc. Thought Question What is the main reason Venus is hotter than Earth? A.Venus is closer to the Sun than Earth. B.Venus is more reflective than Earth. C.Venus is less reflective than Earth. D.The greenhouse effect is much stronger on Venus than on Earth. E.Human activity has led to declining temperatures on Earth.

102 Copyright © 2012 Pearson Education, Inc. What have we learned? Is Venus geologically active? Its surface shows evidence of major volcanism and tectonics during the last billion years. There is no evidence for erosion or plate tectonics. Why is Venus so hot? The runaway greenhouse effect made Venus too hot for liquid oceans. All carbon dioxide remains in the atmosphere, leading to a huge greenhouse effect.

103 Copyright © 2012 Pearson Education, Inc. 7.5 Earth as a Living Planet Our goals for learning: What unique features of Earth are important for human life? How is human activity changing our planet? What makes a planet habitable?

104 Copyright © 2012 Pearson Education, Inc. What unique features of Earth are important for life? 1.Surface liquid water 2.Atmospheric oxygen 3.Plate tectonics 4.Climate stability

105 Copyright © 2012 Pearson Education, Inc. What unique features of Earth are important for life? 1.Surface liquid water 2.Atmospheric oxygen 3.Plate tectonics 4.Climate stability Earths distance from the Sun and moderate greenhouse effect make liquid water possible.

106 Copyright © 2012 Pearson Education, Inc. What unique features of Earth are important for life? 1.Surface liquid water 2.Atmospheric oxygen 3.Plate tectonics 4.Climate stability PHOTOSYNTHESIS (plant life) is required to make high concentrations of O 2, which produces the protective layer of O 3.

107 Copyright © 2012 Pearson Education, Inc. What unique features of Earth are important for life? 1.Surface liquid water 2.Atmospheric oxygen 3.Plate tectonics 4.Climate stability Plate tectonics is an important step in the carbon dioxide cycle.

108 Copyright © 2012 Pearson Education, Inc. Continental Motion Motion of continents can be measured with GPS.

109 Copyright © 2012 Pearson Education, Inc. Continental Motion Idea of continental drift was inspired by puzzle-like fit of continents. Mantle material erupts where seafloor spreads.

110 Copyright © 2012 Pearson Education, Inc. Seafloor Recycling Seafloor is recycled through a process known as subduction.

111 Copyright © 2012 Pearson Education, Inc. Plate Motions Measurements of plate motions tell us past and future layout of continents.

112 Copyright © 2012 Pearson Education, Inc. Carbon Dioxide Cycle 1.Atmospheric CO 2 dissolves in rainwater. 2.Rain erodes minerals that flow into the ocean. 3.Minerals combine with carbon to make rocks on ocean floor.

113 Copyright © 2012 Pearson Education, Inc. Carbon Dioxide Cycle 4.Subduction carries carbonate rocks down into the mantle. 5.Rock melts in mantle and outgases CO 2 back into atmosphere through volcanoes.

114 Copyright © 2012 Pearson Education, Inc. Long-Term Climate Change Changes in Earths axis tilt might lead to ice ages. Widespread ice tends to lower global temperatures by increasing Earths reflectivity. CO 2 from outgassing will build up if oceans are frozen, ultimately raising global temperatures again.

115 Copyright © 2012 Pearson Education, Inc. What unique features of Earth are important for life? 1.Surface liquid water 2.Atmospheric oxygen 3.Plate tectonics 4.Climate stability The CO 2 cycle acts like a thermostat for Earths temperature.

116 Copyright © 2012 Pearson Education, Inc. These unique features are intertwined: Plate tectonics creates climate stability. Climate stability allows liquid water. Liquid water is necessary for life. Life is necessary for atmospheric oxygen. How many other connections between these can you think of?

117 Copyright © 2012 Pearson Education, Inc. How is human activity changing our planet?

118 Copyright © 2012 Pearson Education, Inc. Dangers of Human Activity Human-made CFCs in the atmosphere destroy ozone, reducing protection from UV radiation. Human activity is driving many other species to extinction. Human use of fossil fuels produces greenhouse gases that can cause global warming.

119 Copyright © 2012 Pearson Education, Inc. Global Warming Earths average temperature has increased by 0.5°C in the past 50 years. The concentration of CO 2 is rising rapidly. An unchecked rise in greenhouse gases will eventually lead to global warming.

120 Copyright © 2012 Pearson Education, Inc. CO 2 Concentration Global temperatures have tracked CO 2 concentration for the last 500,000 years. Antarctic air bubbles indicate the current CO 2 concentration is at its highest level in at least 500,000 years.

121 Copyright © 2012 Pearson Education, Inc. CO 2 Concentration Most of the CO 2 increase has happened in the last 50 years!

122 Copyright © 2012 Pearson Education, Inc. Modeling of Climate Change Models of global warming that include human production of greenhouse gases are a better match to the global temperature rise.

123 Copyright © 2012 Pearson Education, Inc. What makes a planet habitable? Located at an optimal distance from the Sun for liquid water to exist

124 Copyright © 2012 Pearson Education, Inc. What makes a planet habitable? Large enough for geological activity to release and retain water and atmosphere

125 Copyright © 2012 Pearson Education, Inc. Planetary Destiny Earth is habitable because it is large enough to remain geologically active, and it is at the right distance from the Sun so oceans could form.

126 Copyright © 2012 Pearson Education, Inc. What have we learned? What unique features of Earth are important for life? Surface liquid water Atmospheric oxygen Plate tectonics Climate stability

127 Copyright © 2012 Pearson Education, Inc. What have we learned? How is human activity changing our planet? Human activity is releasing carbon dioxide into Earths atmosphere, increasing the greenhouse effect and producing global warming. What makes a planet habitable? Earths distance from the Sun allows for liquid water on Earths surface. Earths size allows it to retain an atmosphere and enough internal heat to drive geological activity.


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