Craters of the Moon

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Craters of the Moon

• Read Ch. 4 of the text, sections 4.1 through 4.6

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William Herschel thought he saw 3 volcanos on the
moon in 1787
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Arguments circa 1920 in favor of a volcanic
origin

• Few impact craters known on Earth
• Meteor crater (Barringer crater) in Arizona

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Moon craters are mainly round

• If impacts came in from all directions, wouldnt
  we have more elongated craters?

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Small craters overlap large craters, rather than
vice versa
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Some thought they saw craters in the central
mountain peaks
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Impact origin

• Championed by G.K. Gilbert and others in the 19th
  century, but didnt really take hold until the
  middle of the 20th

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A Michigan native, Ralph Baldwin, helped turn the
argument in favor of impacts
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Baldwin compared craters produced by explosions
on the earth with the craters of the moon

• He found that they followed the same trend of
  diameter versus depth
• Impacts produce a generally round explosive
  crater regardless of direction of impact

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Apollo Landings

• Lunar rocks mainly breccias rocks shattered by
  impacts

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Crater Types
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Simple craters are relatively small
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Complex craters are bigger
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Copernicus
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If Copernicus were 9-inches across, its depth
would be only 1/3 of an inch!
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King Crater
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Basins the Largest impact features
Orientale basin
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Mare Imbrium
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Mare Imbrium
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Mare Humorum