Outline for 31 October Tuesday

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Outline for 31 October (Tuesday)

• The Moon
• Mercury

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Key Words

• anorthosite
• capture theory
• center of mass
• co-creation theory
• collisional ejection theory
• crater
• far side (of the Moon)
• fission theory
• impact breccia
• impact crater
• libration

• lunar highlands
• mare (plural maria)
• mare basalt
• moonquake
• refractory element
• regolith
• synchronous rotation
• terminator
• terrae
• volatile element

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Theories
How did the moon form?

• Getting data to answer this was one of the
  science objectives for the Apollo program.
• What was the (social) driving force for the
  Apollo program?

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Theories
How did the moon form?

• Fission
• Part of Earth tore away because Earth was rapidly
  rotating
• Where did the chunk come from?
• Would expect more similarity in Moon and Earth
  rocks
• Capture
• Wandering moon was captured by Earths gravity
• Computer simulations show that it is highly
  unlikely
• Co-creation
• Formed at same time but separately
• Iron content mismatch
• Collision (collisional ejecta theory)
• Mars-sized object collided with Earth
• Our current best guess

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Question

• The terminator on the Moon is a line  
• A) joining north and south lunar poles, passing
  through the center of the largest mare, Imbrium,
  representing 0 of lunar longitude.
• B) between the near and far sides of the Moon.
• C) between the solar-illuminated and dark
  hemispheres.
• D) along the equator, between northern and
  southern hemispheres.

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Question

• The terminator on the Moon is a line  
• A) joining north and south lunar poles, passing
  through the center of the largest mare, Imbrium,
  representing 0 of lunar longitude.
• B) between the near and far sides of the Moon.
• C) between the solar-illuminated and dark
  hemispheres.
• D) along the equator, between northern and
  southern hemispheres.

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Question

• If you were standing on the Moon with Earth in
  view, how much time would elapse between two
  successive "Earthrises"?
• A) about 1 synodic month
• B) about 1 day
• C) about 1 sidereal month
• D) infinite time, because the same side of the
  Moon always faces toward Earth

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Question

• If you were standing on the Moon with Earth in
  view, how much time would elapse between two
  successive "Earthrises"?
• A) about 1 synodic month
• B) about 1 day
• C) about 1 sidereal month
• D) infinite time, because the same side of the
  Moon always faces toward Earth

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Question

• Maria are
• A) bright streaks radiating away from young,
  fresh craters.
• B) isolated regions of heavily cratered highland
  terrain.
• C) long, sinuous valleys formed by ancient lava
  rivers.
• D) ancient lava floodplains.

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Question

• Maria are
• A) bright streaks radiating away from young,
  fresh craters.
• B) isolated regions of heavily cratered highland
  terrain.
• C) long, sinuous valleys formed by ancient lava
  rivers.
• D) ancient lava floodplains.

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Outline for 31 October (Tuesday)

• The Moon (20 minutes)
• Mercury (55 minutes)

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Interesting facts

• Mariner 10 visited in 1974 and 1975

• MESSENGER (MErcury Surface, Space ENvironment,
  GEochemistry, and Ranging) will orbit starting in
  2011

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Key Terms

• greatest eastern elongation
• greatest western elongation
• solar transit
• 1-to-1 spin-orbit coupling
• 3-to-2 spin-orbit coupling
• scarp

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Observations

• Observing Mercury
• What are best conditions to observe
• Unusual spin
• How suspected to be unusual
• Why unusual
• How verified
• How to make a guess that will make you famous
• Craters
• How similar to the moon
• How different
• Unexpected magnetic field
• Why unexpected
• How measured

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It is hard to see!
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Visualizing Mercurys orbit
(Textbook Chapter 11 online material)
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Visualizing Mercurys orbit
WD
(Textbook Chapter 11 online material)
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Observations

• Observing Mercury
• What are best conditions to observe
• Unusual spin
• How suspected to be unusual
• Why unusual
• How verified
• How to make a guess that will make you famous
• Craters
• How similar to the moon
• How different
• Unexpected magnetic field
• Why unexpected
• How measured

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No-name rotation
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synchronous rotation
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The Moons rotation always keeps the same face
toward the Earth due to synchronous rotation
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Draw ball and arrow at A, B, C, D
C
D
B
A
Mercurys orbital period is 88 days Mercurys
rotation period is 58 days
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Draw ball and arrow at A, B, C, D
C
D
B
A
Mercurys orbital period is 88 days Mercurys
rotation period is 58 days
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Draw ball and arrow at A, B, C, D
C
D
B
A
88/4 22 days to get to A
Mercurys orbital period is 88 days Mercurys
rotation period is 58 days
22/58 0.375
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Draw ball and arrow at A, B, C, D
First rotate around Mercurys axis. Then move
into position in orbit.
C
0.375 of a full turn
D
B
A
88/4 22 days to get to A
Mercurys orbital period is 88 days Mercurys
rotation period is 58.6 days
22/58 0.375
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Draw ball and arrow at A, B, C, D
C
D
D
B
A
88/4 22 days to get to A
Mercurys orbital period is 88 days Mercurys
rotation period is 58 days
22/58 0.375
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C
1.125 turns
D
0.75 of a full turn
B
1.5 turns
0.375 of a turn
A
A
88/4 22 days to get to A
Mercurys orbital period is 88 days Mercurys
rotation period is 58 days
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Observations

• Observing Mercury
• What are best conditions to observe
• Unusual spin
• How suspected to be unusual
• Why unusual
• How verified
• How to make a guess that will make you famous
• Craters
• How similar to the moon
• How different
• Unexpected magnetic field
• Why unexpected
• How measured

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• Heavily cratered surface
• Less dense cratering than moon
• Gently rolling plains
• Scarps
• No evidence of tectonics

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• Note how much more densely the craters occur on
  the moons surface.

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• Scarps are cliffs
• This one is more than a km high
• They probably formed as the planet cooled and
  shrank

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• The Caloris Basin is evidence of a large impact

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• The seismic waves from the impact that caused the
  Caloris Basin caused this deformation on the
  opposite side of Mercury

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Observations

• Observing Mercury
• What are best conditions to observe
• Unusual spin
• How suspected to be unusual
• Why unusual
• How verified
• How to make a guess that will make you famous
• Craters
• How similar to the moon
• How different
• Unexpected magnetic field
• Why unexpected
• How measured

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The magnetosphere blocks the solar wind from
reaching the surface of the planet
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Questions

• 6.It is relatively difficult to observe details
  on the surface of Mercury from Earth because
• A) detail is obscured by bright glows from hot
  regions of molten surface heated by the intense
  sunlight.
• B) its orbit always keeps it on the opposite side
  of the Sun from Earth.
• C) it is a small object that always appears close
  to the Sun in the sky.
• D) its surface is always completely covered in
  clouds.

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Questions

• 6.It is relatively difficult to observe details
  on the surface of Mercury from Earth because
• A) detail is obscured by bright glows from hot
  regions of molten surface heated by the intense
  sunlight.
• B) its orbit always keeps it on the opposite side
  of the Sun from Earth.
• C) it is a small object that always appears close
  to the Sun in the sky.
• D) its surface is always completely covered in
  clouds.

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Questions

• The reason the temperature on the dark side of
  Mercury is warmer than originally expected is
  that
• A) Mercury's large iron core conducts heat
  through the planet.
• B) Mercury does not rotate synchronously with its
  orbital period.
• C) several very active volcanoes on Mercury,
  produced by tidal stresses from the Sun, produce
  excess heat.
• D) winds in Mercury's tenuous atmosphere carry
  heat from the daytime side to the night side.

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Questions

• The reason the temperature on the dark side of
  Mercury is warmer than originally expected is
  that
• A) Mercury's large iron core conducts heat
  through the planet.
• B) Mercury does not rotate synchronously with its
  orbital period.
• C) several very active volcanoes on Mercury,
  produced by tidal stresses from the Sun, produce
  excess heat.
• D) winds in Mercury's tenuous atmosphere carry
  heat from the daytime side to the night side.

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Questions

• What is believed to be the cause of the long,
  meandering scarps (cliffs) observed on Mercury?
• A) shrinkage of the planet as Mercury cooled
• B) large impacts near the end of the early period
  of heavy bombardment
• C) volcanic eruptions along crustal faults over
  hot spots in the mantle
• D) crustal movement due to convection in the
  mantle, similar to continental drift on Earth but
  to a much smaller extent

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Questions

• What is believed to be the cause of the long,
  meandering scarps (cliffs) observed on Mercury?
• A) shrinkage of the planet as Mercury cooled
• B) large impacts near the end of the early period
  of heavy bombardment
• C) volcanic eruptions along crustal faults over
  hot spots in the mantle
• D) crustal movement due to convection in the
  mantle, similar to continental drift on Earth but
  to a much smaller extent