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Name
Date
Class
Models of the Solar System
Inquiry Warm-Up, What Is at the Center?
In the Inquiry Warm-Up, you investigated whether Earth or the sun is at the center of the
solar system. Using what you learned from that activity, answer the questions below.
1. INFER Why did early astronomers believe the sun revolved
around Earth?
2. COMMUNICATE Draw and label a diagram of Step 2.
3. COMMUNICATE Draw and label a diagram of Step 4.
4. ANALYZE SOURCES OF ERROR What would early astronomers have
needed to have a better understanding of the position of Earth and
the sun?
81A
Name
Date
Models of the Solar System
What Was the Geocentric Model?
I get it! Now I know that the geocentric model is
I need extra help with
How Did the Heliocentric Model Develop?
1a. REVIEW (Kepler/Copernicus) discovered that planets move in ellipses.
b. RELATE EVIDENCE AND EXPLANATION What discoveries by Galileo
support the heliocentric model?
I get it! Now I know that the heliocentric model was developed
I need extra help with
81B
Class
Name
Date
Class
Models of the Solar System
On a separate sheet of paper, compare and contrast the geocentric model and the
heliocentric model. Underline the name of the model that is correct.
81C
Name
Date
Class
Models of the Solar System
Understanding Main Ideas
Use the diagrams below to answer the questions in the spaces provided.
Ancient Greek Model
Ptolemy‘s Geocentric Model
Copernicus‘s Heliocentric Model
1. What is the main difference between the geocentric and heliocentric
models?
2. How do the ancient Greek model and Ptolemy’s model differ?
3. How did Galileo’s observations of Jupiter and Venus support
Copernicus’s model?
Building Vocabulary
On a separate sheet of paper, write a definition for each of these terms.
4. heliocentric
5. ellipse
6. geocentric
81D
Name
Date
Class
Models of the Solar System
Read the passage and study the diagram below. Then use a separate sheet of paper to
answer the questions that follow.
The Phases of Venus
Why did Galileo infer that the phases of Venus are a result of that planet’s moving around the sun rather
than around Earth? After all, the moon has phases, and it revolves around Earth. The answer lies in how
Venus’s apparent shape and size change. Figure 1 shows Venus at several places in its orbit. Figure 2
shows how Venus would appear at these places if viewed with a telescope from Earth.
The phases of Venus look a lot like those of the moon, including full, half, crescent, and new. There
is an important difference, though. The full Venus looks less than half as wide as the crescent Venus.
This means that when it is full, Venus is much farther away from Earth than when it is crescent or new.
Galileo also knew that Venus is called the morning star or the evening star because it is never very far
from the sun in the sky.
Combining these observations, Galileo reasoned that Venus must revolve around the sun.
1. How is the position of the full moon in relation to Earth and the sun
different from the position of the full Venus in relation to Earth and
the sun? Does the apparent size of the moon change with its phases?
2. Where is the moon located, relative to Earth and the sun, when it is
new? What about Venus?
3. The moon has phases too. Why doesn’t that make us think the moon
revolves around the sun, rather than around Earth?
81E
Name
Date
Class
Models of the Solar System
If the statement is true, write true. If the statement is false, change the underlined word
or words to make the statement true.
1.
Ge is the Greek word for “Earth.”
2.
Helios is the Latin word for “Sun.”
3.
A(n) octagon is an oval shape, such as the planets’ orbits.
4.
Galileo discovered six moons around Jupiter.
Ptolemy’s model explained the motions observed in the sky
5.
fairly accurately.
6.
In ancient times, people could not accept that the sun was the
center of the universe.
Write the letter of the correct answer on the line at the left.
7.
In the late 1500s, Ptolemy’s observations
were supplanted by those of
A later Greek astronomers
B later Polish astronomers
C Edwin Hubble
D Tycho Brahe
9.
People became convinced that the
heliocentric model is correct after evaluating
evidence collected by
A Galileo Galilei
B Nicolaus Copernicus
C Tycho Brahe
D Johannes Kepler
8.
10.
81F
The arrangement of the known
planets and how they move around the
sun was first worked out by
A Galileo Galilei
B Nicolaus Copernicus
C Tycho Brahe
D Johannes Kepler
Earth is at the center of the
revolving planets and stars in a(n)
A heliocentric model
B astrological model
C geocentric model
D Copernican model