Download Lesson 5 Geocentric v Heliocentric Models

Trivia Question of the Day
Astronomy Picture of the Day
Review Questions
(on a separate sheet of paper)
1. Write down ONE piece of evidence that
supports the Big Bang Theory.
Review Questions
2. List the following in order from OLDEST to
YOUNGEST:
-
- Solar system
Milky Way galaxy
- Universe
Review Questions
3. In which part of the H-R diagram do stars
spend most of their lives?
Review Questions
4.
Review Questions
5. The 4 terrestrial planets include…
6. The 4 jovian planets include…
Review Questions
7. How is rotation different from revolution?
Review Questions
8. Which of the following are MORE eccentric?
A.
B.
Review Questions
9. How could we move the foci to make this ellipse
MORE round?
10. How could we move the foci to make this ellipse
MORE eccentric?
Review Questions
11. At what time of year is the Earth at
perihelion?
12. At what time of year is the Earth at
aphelion?
Lesson 5:
Geocentric vs.
Heliocentric
Models of
Apparent Motions
What are
“Apparent Motions”?
►A
motion that an object appears to make
► Can be real or an illusion
► For example,
 A person is spinning around = real motion
 The spinning person sees the room as spinning
= apparent motion
► Earth’s rotation causes the apparent motions of
celestial objects (the Sun, moon, stars, and
planets) across our sky
So what do apparent motions
have to do with astronomy???
►
Every day and night throughout the year, when you
look up in the sky, what do you see moving???
 The Sun
 The Moon
 The Stars
 Some of the Planets
For thousands of years, people have had ideas,
theories and models to explain why these
objects APPEAR to move the way they do…
Geocentric Models
► Key
Ideas:
 “Geo” = Earth
 “Centric” = Center
► “Earth-centered”
 Earth is the center of the solar system
 Earth is stationary (not moving) and everything is
moving around us
In your notes, draw a picture of what the
geocentric model looks like…
Geocentric Models
► Key
Limitations:
 Did not explain the apparent motions of some
planets (for example, Mars)
 Did not explain all of Earth’s motions, including how
a freely-swinging pendulum moves
Heliocentric Models
► Key
Ideas:
 “Helio” = Sun
 “Centric” = Center
► “Sun-centered”
 The Sun is the center of the solar system
 Earth rotates on its own axis AND revolves around
the Sun
In your notes, draw a picture of what the
heliocentric model looks like…
Heliocentric Models
► Key
Limitations:
 The early models used circular orbits  did not
explain the apparent motions of planets
(BUT… once elliptical orbits and planets’ orbital
speeds were added to the model,
the planets’ apparent motions could be explained
and even predicted!)
Challenge Question
► Write
down one SIMILARITY between the
geocentric and heliocentric models
► Write
down one DIFFERENCE between the
geocentric and heliocentric models
Practice Problems
&
Homework #4