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Homework

Homework. Is there a good scientific question? Is there a good explanation for why the topic/question is worthy of research? Is there a good hypothesis (if / then)? Are there at least 10 quality sources? Will the project need special approval?

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Homework

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  1. Homework • Is there a good scientific question? • Is there a good explanation for why the topic/question is worthy of research? • Is there a good hypothesis (if / then)? • Are there at least 10 quality sources? • Will the project need special approval? • What questions or comments do you have for the person?

  2. The Earth’s Moon 09.10.07 / 09.11.07

  3. Concept: The Moon • EQ: What hypotheses have been developed to explain the evolution of the Moon?

  4. Earth's Moon General characteristics • Size • unusually large relative to the Earth • Most satellites are much smaller than their parent planets. • Density • Comparable to Earth's crust • Too low to contain a significant iron core

  5. Earth's Moon General characteristics • No atmosphere • Tectonics no longer active • Surface is bombarded by small meteorites which slowly smoothes the landscape • Oldest rocks are about 4.5 by, in contrast to Earth’s oldest rock, which 3.8 by

  6. Lunar topography

  7. Lunar Surface Two types of terrain • Maria (singular, mare), Latin for "sea“ • Highlands, English for land that is high

  8. Lunar surface Maria • Dark region • Fairly smooth lowlands • Originated from asteroid impacts and lava flooding the surface • Form most of the near side of Moon • Were once thought to be seas because of their dark color

  9. Formation of Maria

  10. Lunar surface Lunar highlands • Bright, densely cratered regions • Bright, densely cratered regions • Make up most of the Moon • Make up nearly all of the far side of the Moon • Older than maria

  11. Craters • Produced by an impact from a meteoroid which produces • Ejecta • Rays (associated with younger craters) • Craters within craters are common • Crater layering can be used for relative dating

  12. A 20-kilometer-wide crater on the Moon

  13. The Copernicus crater is 93 km wide.

  14. Graphic: from Lunar and Planetary Institute

  15. Earth’s Moon • Central Peaks The physics of large impacts are mind-boggling…. The rocks are subjected to stresses hundreds of times their failure strengths. This means that the rocks effectively behave as if they were water…. They flow plastically as if they were fluids. Source: http://www.uwgb.edu/dutchs/planets/cratform.htm

  16. Source: http://www.uwgb.edu/dutchs/planets/cratform.htm

  17. Check up • How are central peaks formed? • What are maria? • Why are highlands more cratered than maria? • What is a major visual difference between the near side and far side of the Moon?

  18. Lunar Regolith • Regolith means “blanket” • Covers all lunar terrains • Gray, unconsolidated debris • Soil-like layer produced by meteoric bombardment • Varies in depth from about 2 – 20 meters • Regolith on earth produced by weathering

  19. Lunar Regolith

  20. Where did it come from? • Hypothesis 1: fission (daughter) • Moon was ejected from Earth • Mathematical models show it is impossible • Hypothesis 2: coaccretion (sister) • Earth and Moon formed together from same material • Cannot explain Moon’s lack of core • Hypothesis 3: capture (spouse) • Moon was another planet caught by Earth’s gravity • Cannot explain why Moon and Earth are so chemically similar • This is very unlikely to ever happen

  21. Giant Impact Hypothesis • A Mars-sized object hit the Earth in our planet’s early history • Material was ejected into orbit and formed Moon • Has been supported by mathematical model • Explains why the Moon: • is very similar in age to Earth • has identical materials to Earth’s crust • does not have an iron core

  22. Check up • Describe the three models of Lunar evolution that were replaced by the giant impact hypothesis. • Describe evidence for the giant impact hypothesis • Why are regolith on highlands thicker than on maria? • How can scientists determine relative ages of Lunar craters?

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