Our Barren Moon twlee2016@gmail.com

Chapter 7 twlee2016@gmail.com

Chapter 7
Our Barren Moon twlee2016@gmail.com

Chapter 7
The seismograph placed on the Moon by the
Astronauts of the Apollo Program twlee2016@gmail.com

Chapter 7
Does the moon rotate?
What if the
Moon did not rotate?
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Chapter 8
Our Barren Moon
Synchronous Rotation
One rotation for one revolution twlee2016@gmail.com

Lunar Phases as described by
Aristotle
We only see the lighted portion of the
Moon
Chapter 7 twlee2016@gmail.com

Chapter 7
Surface Features
Craters on the Moon and the
Earth
Impact
Maria, Basins, Rays
Impact and volcanism
Rills and Domes
Volcanism twlee2016@gmail.com

Craters,
Maria and
Basins are all due to meteorite impact
Chapter 7 twlee2016@gmail.com

Chapter 7
Moon has large dark flat areas, due to impact and lava flow, called maria or basins (early observers thought the basins were oceans or seas) twlee2016@gmail.com

Chapter 7
Craters have round bottoms, flat bottoms and flat bottoms with a hump depending on the energy deposited .
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Chapter 7
Far side of Moon has some large craters, but no large maria. The reason for this difference is still not fully understood
.
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Chapter 7
Meteoroid strikes Moon, ejecting material; explosion ejects more material; leaving crater, lips (rim) and ejecta twlee2016@gmail.com

Chapter 7
The surface of the moon is heavily cratered. One of the results of the infalling bodies is to pulverize the surface, thus creating a layer debris, much of it is very fine dust. The surfaced is layered with debris on top of pulverized rock
.
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Chapter 7
Most lunar craters date to at least 3.9 billion years ago; much less bombardment since then.
Craters are typically about 10 times as wide as the meteoroid creating them, and twice as deep as they are wide.
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Chapter 7
Early Intense
Bombardment twlee2016@gmail.com

Chapter 7
Moon is still being bombarded by very small objects called
“micrometeorites” which trends to round the edges of craters and leave a layer of dust. twlee2016@gmail.com

Chapter 7
Meteorites also hit Earth; this crater is in
Arizona twlee2016@gmail.com

Chapter 7
The great “lakes “ of liquid rock that filled the large craters are greatest evidence of vulcanism on the moon. Vulcanism ceased when the moon cooled .
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Chapter 7
This is an edge of a mare. The sooth appearance is due to the lava that flowed up through cracks , smoothed out then cooled . twlee2016@gmail.com

Chapter 7
Hadley Rill seems to be an extended lava tube whose roof has fallen in.
There are other caved in lava tubes but they are much shorter, twlee2016@gmail.com

Chapter 7
Domes can not be explained by meteorite impact
Field of Domes twlee2016@gmail.com

Chapter 7
Moon’s density is relatively low, and it has no magnetic field – cannot have sizeable iron/nickel core. Due to cooling over time the crust has thickened.
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Chapter 7
Why Air Sticks Around
Air molecules have high speeds due to thermal motion. If the average molecular speed is well below the escape velocity, few molecules will escape.
Escape becomes more probable:
• for lighter molecules (higher speed for same kinetic energy)
• at higher temperatures
• for smaller planets (escape speed is less) twlee2016@gmail.com

Chapter 7
Early theories of the origin of the Moon twlee2016@gmail.com

Chapter 7
The currant, post Apollo, theory is the
Collision Ejection Theory. Two large planetismals collide. Their crusts splash, their interiors merge. The merged interiors become the Earth. The splashed crustal material becomes the Moon.
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Chapter 7
This theory accounts for the difference in density of the Moon and Earth, the reason for the high percentage of iron in the Earth, and the strange orbital placement.
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Chapter 7
Time
4.6 billion yr (?)
3.9 billion yr
3.2 billion yr
Event
Formation of Moon; heavy bombardment
Bombardment much less intense; lunar volcanism fills maria
Volcanic activity ceases twlee2016@gmail.com

Chapter 7
The early history of the moon includes the Early Intense
Bombardment which is the last step in the accretion process.
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Chapter 7
End Chapter 7 twlee2016@gmail.com