Announcement... Extra Credit!

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Announcement... Extra Credit!

• See a planetarium show at Museum of the Rockies
• Sky Quest
• Current Sky
• Not a laser show or a kids show!
• Sign in at the front desk.
• Free admission!
• 20 points same as an activity!
• One time only. By the last day of classes!

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Announcement... Extra Credit!
Taylor Planetarium current schedule
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Developing a model of the solar system

• Review
• Spherical Earth
• Motion of the stars
• Motion of the Sun Moon

• Solar System
• Geocentric models
• Aristotle
• Ptolemy
• Copernicus

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Models of the solar system

• Stars move each night
• Sun moves through the stars throughout the year
• Planets
• move slowly through the stars
• planet means wandering star
• Earth-centered or Sun-centered

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Aristotles model (384-322 BC)
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Problem retrograde motion

• Planets sometimes back up!
• Aristotles model doesnt do that.

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Retrograde motion of Mars
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion of Mars
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Retrograde motion of Mars
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Retrograde motion of Mars
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Retrograde motion of Mars
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Retrograde motion of Mars
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Retrograde motion of Mars
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Retrograde motion of Mars
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Retrograde motion of Mars
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Retrograde motion of Mars
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Retrograde motion of Mars
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Retrograde motion of Mars
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Retrograde motion of Mars
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Cladius Ptolemy (85-165)

• Earth is at the center
• Earth is imperfect, celestial sphere is perfect
• Circles govern heavenly motions

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Ptolemysgeocentric model
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Retrograde motion (Ptolemy)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Retrograde motion (Ptolemy)
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Epicycle
Ptolemys model was actually even more
complicated.
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Copernicus heliocentric model

• Ptolemys model was used for almost 1400 years.
• Copernicus proposed a very different model in
  1543
• Planets, including Earth, move around Sun.
• Retrograde motion is explained without epicycles.

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Retrograde motion
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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Retrograde motion (Copernicus)
http//www.lasalle.edu/smithsc/Astronomy/retrogra
d.html
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In class writing
If you lived in the year 1543, which would you
believe Copernicus model (Sun-centered) or
Ptolemys model (Earth-centered)? Why?

• Discuss some examples of questions science can
  answer and some questions science cannot answer

How are the latter questions answered?
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Do you use WebCT?

1. Yes, I love it
2. Yes, but I dont love it
3. No
4. No, I hate it
5. Whats WebCT?

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Team activity 12

• Dont forget your team
• Skip tracing orbits in part II, but do question
  3.