Prehistoric and Classic Astronomy
Warm Up Questions
CPS Questions (1-2)
Chapter 1, Lesson 1
Chapter Overview
 Prehistoric and Classical Astronomy
 Astronomy and the Renaissance
 The Enlightenment and Modern
Astronomy
Chapter 1, Lesson 1
Lesson Overview
 Celestial Sphere
 Greek Earth-Centered Model
 Ptolemy’s Model
Chapter 1, Lesson 1
Quick Write
What does Eratosthenes’ experience in
measuring the Earth tell you about what’s
needed for scientific discoveries?
(Note to teacher: Use “Pick a Student” button in CPS)
Chapter 1, Lesson 1
The Celestial Sphere
Celestial sphere refers
to an imaginary sphere
of heavenly objects that
seems to center on the
observer
North Celestial Pole
South Celestial Pole
Constellation
Courtesy of NOAO/AURA/ASF
Chapter 1, Lesson 1
The Celestial Sphere
 It takes the Sun about 365.25
days to revolve around the
celestial sphere
 The ecliptic is the name for
the Sun’s apparent path among
the stars around the Earth
 The zodiac is the group of
constellations the Sun passes
through on its apparent path
along the ecliptic
Chapter 1, Lesson 1
The Moon’s Phases
The Moon does
orbit the Earth
Earth’s gravity
holds the Moon in
such a firm grip
that it always
keeps the same
face turned toward
the Earth
Chapter 1, Lesson 1
The Moon’s Phases
Chapter 1, Lesson 1
© J. Gatherum/ShutterStock, Inc.
Observing Planetary Motion
Retrograde Motion
Planets move in
elliptical, not circular
orbits
Revolve around the
Sun, not Earth
Chapter 1, Lesson 1
The Greek Earth-Centered Model
Thales of Mileus
Stars are not gods
Pythagoras
Spherical Earth
Aristotle – 322 BC
Placed the Earth at the center of things
Parallax is the apparent shifting of nearby
objects with respect to distant ones as the
position of the observer changes
Chapter 1, Lesson 1
Ptolemy’s Model
Claudius Ptolemy – AD 150
Ptolemy believed that heavenly bodies
(planets and stars) were perfect, in contrast to
earthbound objects
The universe was based on perfect circles
 An epicycle is the circular orbit of a
planet, the center of which revolves
around the Earth in another circle
Chapter 1, Lesson 1
Evaluating Ptolemy’s Model
Strengths
 Fits evidence
available during his
lifetime
 Includes testable
predictions
Weaknesses
 Assumed that Earth
was stationary
 Theory of epicycles
was a departure from
simplicity and
symmetry
Chapter 1, Lesson 1
Learning Check
CPS Questions (3-4)
Chapter 1, Lesson 1
Activity 1: Astronomy Crossword
Use your textbook to identify the
terms and people of prehistoric and
classical astronomy to complete the
crossword puzzle.
Refer to pages 6-18 in the textbook.
Chapter 1, Lesson 1
Activity 2: Testing Parallax
Follow the step-by-step directions on
your worksheet in order to test the
concept of parallax.
Then answer the questions about
parallax on the worksheet.
Be prepared to share your answers
with the class.
Chapter 1, Lesson 1
Activity 3: The Moon’s Phases
Work with your team to complete your
worksheet on the Moon’s phases.
You may refer to page 13 in the
textbook.
Chapter 1, Lesson 1
Technology Enrichment:
Sky Maps & Constellations
1. Using the website link provided,
download this month’s version and last
month’s version of the Evening Sky Map
for your geographic location.
2. Follow the steps and answer the
questions on the worksheet. You may
refer to pages 9-10 in your textbook.
Chapter 1, Lesson 1
Review
 Celestial sphere refers to an imaginary sphere
of heavenly objects that seems to center on the
observer
 Earth’s gravity holds the Moon in such a firm grip
that it always keeps the same face turned
toward the Earth
 The ancient Greeks looked for symmetry, order,
and unity in the cosmos
 Thales of Miletus reasoned that the Sun and
other stars were not gods but balls of fire
Chapter 1, Lesson 1
Review, cont.
 Pythagoras proposed that the Earth is spherical
 Aristotle placed the Earth at the center of things
 The Greek model of the universe that won the
widest acceptance was that of Claudius
Ptolemy; for 1,300 years, his model was the
conventional wisdom of the scientific world
Chapter 1, Lesson 1
Review Questions
CPS Questions (5-6)
Chapter 1, Lesson 1
Summary
 The Celestial Sphere
 Greek Earth-Centered Models
 Ptolemy’s Model
Chapter 1, Lesson 1
Next…
Done – Prehistoric
and Classical
Astronomy
Next – Astronomy
and the
Renaissance
Chapter 1, Lesson 1
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