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Why Do You Think All the Terrestrial Planets Were So Hot in the Past? Isn’T Space Rather Cold?

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Why Do You Think All the Terrestrial Planets Were So Hot in the Past? Isn’T Space Rather Cold? Terrestrial Planets Discussion Why do you think all the terrestrial planets were so hot in the past? Isn’t space rather cold? Discussion What’s a silicate? Give and example of a silicate. Discussion How do you think we know what the internal structure of the Earth is when our deepest mines and wells have not made it deeper than the Earth’s crust? Earthquakes Earthquakes produce three types of waves that travel through the Earth. 1. Surface waves 2. Primary waves, or P waves 3. Secondary waves, of S waves Discussion Which type a wave do you think will travel beJer through a liquid and why? Discussion How do you think we know that the Earth’s inner core is solid? Planetary MagneLc Fields Caused by moLon of charged parLcles Requires, moderately rapid rotaon, molten core and convecLon Planets internal structure Two tools without seismic data: 1) Mean density 2) Gravitaonal mapping – mascons Discussion Which of the terrestrial worlds likely was the hoJest during formaon? Why? Planetary Size and Cooling Larger planets lose heat more slowly than do smaller planets. Discussion Larger planets have larger surface areas, and a larger surface area should radiate more energy into space? So shouldn’t larger planets cool faster? Why do larger planets cool more slowly than smaller planets? Geologic acLvity Internal heat drives geologic acLvity on the planets’ surfaces. Discussion Because heat is radiated from the surface of a planet, the surface is cooler than the interior. How does the heat from the core of the planet get to the surface? Plate tectonics Geologic processes 1) Impact cratering 2) Volcanism 3) Tectonics 4) Erosion Impact Craters and Surface Age The more impact craters on a surface, the older that surface is. Discussion Which area on the Moon is older, the light region to the leY or the dark region in the center of the picture? Discussion Rank the terrestrial planets (include the Moon) in terms of the age of their surfaces from youngest to oldest to try and predict which planets will have the most craters. 1. Earth 2. Venus 3. Mars 4. Mercury 5. Moon Smaller planets retain less heat and therefore have less geologic acLvity. Discussion Why do you think Earth’s oceans have so few impact craters as compared to Earth’s conLnents? Venus radar map Mars laser alLmeter map Types of craters 1) Simple 2) Complex 3) MulL-ringed basin Moltke Crater (7 km) Bessel crater (16 km) Euler Crater (25 km) King Crater (77 km) Copernicus Crater (95 km) Schrodinger (320 km) Mare Orientale (930 km) Mare Imbrium (1100 km) Mercury Colaris basin Mercury (1550 km) ChaoLc terrain formaon Meteor Crater (1.2 km) Arizona from the ShuJle Wolf Creek (0.85 km) New Quebec Crater (3.4 km) Clearwater Lakes (26 km) Chichxulub Crater (250 km) Manicouagan Crater (100 km) Discussion Why is the Manicouagan crater inverted, with a lower rim and higher center? Hint: It is at high northern latude and is rather old (212 million years) Radar images of Venus Bright areas in radar images indicate rough terrain, while dark areas are smooth. Typically, rough terrain is younger than smooth terrain. Discussion Why are rough areas younger? Adivar Venus (29 km) Meitner basin Venus (150 km) Unnamed crater Mars (2.3 km) Hellas basin Mars (2000 km) Discussion NoLce the small size of this crater (about 12 km). On the Moon complex craters were about twice as large. What does this tell you about the surface material of Mars where this crater formed? Why are craters important • Numbers of craters provide relave ages • Punch holes in crust • TransiLon size between simple and complex craters provides clues to the melLng point/strength of the surface. .
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