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The Enlightenment and
Modern Astronomy
Warm Up Questions
CPS Questions (1-2)
Chapter 1, Lesson 3
Lesson Overview
 Galileo and the Telescope
 Newton’s Laws of Motion and Gravity
 Einstein and Relativity
Chapter 1, Lesson 3
Quick Write
Which do you think is more important for
real scientific progress – curiosity and
imagination, or up-to-date scientific tools?
(Note to teacher: Use “Pick a Student” button in CPS)
Chapter 1, Lesson 3
Galileo and the Telescope
 Galileo did not invent
the telescope but he
was the first person to
use a telescope to
study the sky
Chapter 1, Lesson 3
© National Library of Medicine
Galileo and the Telescope, cont.
Galileo made observations such as
mountains and valleys on the Moon
many more stars than can be observed with
the naked eye
These ideas were unsettling to those
who believed in “perfection of the
heavens”
Chapter 1, Lesson 3
Jupiter’s Four Moons
Four moons revolved around Jupiter
Io, Europa, Ganymede and Callisto never
appear north or south of Jupiter
Suggested to Galileo that their orbital
plane aligned with that of Earth
Contradicted the theory that Earth must be
stationary or it would lose its Moon
Chapter 1, Lesson 3
Phases of Venus
Venus has phases like those of Earth’s Moon
Chapter 1, Lesson 3
Courtesy Lowell Observatory
Phases of Venus, cont.
Venus seems to change size
Arc of Venus’s crescent is much larger
than the full Venus, showing that it is
significantly closer to Earth
Supports the Sun-centered model
Chapter 1, Lesson 3
Newton’s Three Laws of Motion
Inertia - the tendency of
an object to resist a
change in its motion
Newton’s First Law of
Motion: A body in motion
tends to stay in motion,
and a body at rest tends to
stay at rest
Chapter 1, Lesson 3
©Photos.com
Newton’s Three Laws of
Motion, cont.
Newton’s Second Law
A) The wheeled brick will accelerate
B) if a force is exerted on it.
C) If twice as much force is exerted on it,
it will accelerate at twice the rate.
Chapter 1, Lesson 3
The same amount of force will
give twice as much mass only
half the acceleration.
Newton’s Three Laws of
Motion, cont.
 Newton’s Second Law: How much
force is necessary to produce a certain
acceleration of an object
 Force = mass x acceleration (F=ma)
OR acceleration = Force ÷ mass
(a=F/m)
 Newton’s Third Law of Motion: For
every action there is an equal and
opposite reaction
Chapter 1, Lesson 3
The Law of Gravity
 Every object in the universe attracts every other
one
 The greater the mass of an object, the greater
the attractive force it exerts on other objects
 On Earth the force of gravity made objects fall to
the ground
 Gravity also held the Moon in orbit around the
Earth, and the planets in their orbits around the
Sun
Chapter 1, Lesson 3
How Newton’s Laws
Confirmed Kepler’s
Sun as the source of the force responsible
for the motion of the planets
The gravitational force acting on an object
orbiting the Sun (or other stationary body)
always points toward the Sun
Laws of motion and gravity can be applied
to any two objects orbiting each other
Chapter 1, Lesson 3
Einstein and Relativity
Principle of Equivalence –
effects of acceleration are
indistinguishable from
gravitational effects
Chapter 1, Lesson 3
© AIP Emilio Segrè Visual Archives
Einstein and Relativity
Einstein proposed thinking of space as
being curved by a mass – objects move
because of the curvature
Three dimensions are needed to describe
the position of something
North-South
East-West
Up-Down
Chapter 1, Lesson 3
Testing the Bending of Light
 It takes a very massive object to bend
light with gravity in an amount you can
detect
 During the 1919
eclipse, light from
two stars bends and
makes the stars
appear farther apart
Chapter 1, Lesson 3
Constant Speed of Light Proves the
Special Theory of Relativity
No place in the universe is stationary or “at
rest”
Light always travels at the same speed
regardless of the observer’s speed
Mass (m) can be transformed into energy
(E) E=mc2
The first explosion of a nuclear bomb
confirmed this equation in 1945
Chapter 1, Lesson 3
Learning Check
CPS Questions (3-4)
Chapter 1, Lesson 3
Activity 1: Modern Astronomy
Matching
Match the term with it’s definition or explanation
Chapter 1, Lesson 3
Activity 2: Newton’s First Law of
Motion
1. Stack the sugar cubes to make a tower.
2. Lay the ruler flat on the table. Swing the ruler
sideways quickly so that you only hit the
bottom sugar cube.
3. Stack the sugar cubes again. Try removing
the sugar cubes one by one without knocking
over the tower.
Chapter 1, Lesson 3
Activity 3: Newton’s Second Law of
Motion
1.
2.
3.
4.
Tie the string around the outside edge of one eraser.
Attach the paper clip to the string on one of the narrow
edges of the eraser. Stack the remaining erasers on
top of the first eraser.
Hook the spring scale to the paper clip and slowly pull
the stack of erasers across a table.
Remove the top eraser. Pull the remaining two
erasers across the table using the same amount of
force you used in step 2.
Repeat step 3 using just one eraser. Try to use the
same amount of force as you did in step 2.
Chapter 1, Lesson 3
Technology Enrichment:
Four Forces
Answer the questions on the worksheet
after watching the video clip from NASA
about the forces in action on an airplane in
flight.
If you are unable to watch the video,
research the answers to the questions on
the worksheet about the forces of flight
using a search engine, such as google.com
or yahoo.com.
Chapter 1, Lesson 3
Review
Galileo used the telescope to make
observations that informed the debate
between heliocentric and geocentric
theories
Sir Isaac Newton was the first to create a
unified model of how the universe works
Scientists’ much greater understanding of
the universe would not have been possible
without Einstein
Chapter 1, Lesson 3
Review Questions
CPS Questions (5-6)
Chapter 1, Lesson 3
Summary
 Galileo and the Telescope
 Newton’s Laws of Motion and Gravity
 Einstein and Relativity
Chapter 1, Lesson 3
Next…
Done - Enlightenment and
Modern Astronomy
Next - Earth: Inside and
Out
Chapter 1, Lesson 3
Courtesy of NASA