Ancient
astronomy
Geocentric
Heliocentric
Mass and
Gravity
Galileo
Kepler
Newton
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Tycho Brahe and Kepler
The reason scientist no longer
accept the Ptolemaic model is
due to the work of
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Orbits of planets are circular
Ptlomey and Copernicus
Incorrectly agreed that
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Venus and Mercury
A fatal flaw of Ptolemy’s
model is it’s inability to
predict the phases of
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Aristarchus
The heliocentric model was
actually first proposed by:
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Ptolemy used epicycles for Venus to explain the earth
centered universe, which could not explain why we see
a full Venus phase. Galileo observe that Venus goes
through a full Venus cycle and therefor the sun must be
in the center
How did Galileo’s observations
of Venus disprove Ptolemy?
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Copernicus
Who did Kepler correct by
describing orbits as elliptical
rather than circular?
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The moon orbiting the Earth
What celestial relationship is
the same in both the
heliocentric and geocentric
models?
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Brahe
Whose detailed observations
led to Kepler’s Laws
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Show me your answers
Name three differences between
the geocentric and heliocentric
models
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The Earth moves faster than these outer
world, so we overtake them and as we
sweep past them they appear to go
westward for a few weeks
Explain how Copernicus
accounts for the retrograde
loops of the superior planets
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Overcome the gravitational pull of an object
Escape velocity is the speed
required to
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One fourth as great
If the distance between two
asteroids is doubled, the
gravitational force they exert
on each other will be
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The mean distance between the Earth and
Sun?
What is an Astronomical
Unit?
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Decrease by a factor of 9
If the Moon was three times
further from Earth, the force
by Earth on the Moon would
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The higher the eccentricity the more elongated
the oval, a circle has an eccentricity of zero
Explain how eccentricity
describes the shape of an
ellipse
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Jupiter
Galileo’s discovery of four
moons orbiting ________
helped support the ideas of
Copernicus
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He laid out the order and relative motion on
the known solar system
What contribution did
Copernicus make that helped
Galileo in his observations?
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Sunspots which rotated across the sun’s face
What did Galileo discover
when looking at the sun?
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Sunspots, Venus phase cycle Four moons
around Jupiter Craters and mare on the Moon
What are three things Galileo discovered through his
telescope?
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Galileo found Venus went through an entire
phase cycle which could only happen in the
Copernican model
How did Galileo’s
observations of Venus
disprove the Ptolemaic
model?
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Kepler
Whose laws described
Planetary motion
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The orbits of the planets are ellipses with
one focus at the sun.
What point do Copernicus
and Kepler disagree?
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Proportional to the cube of its semi-major
axis
According to Kepler’s third
law, the square of the planet’s
period in years is
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Planets further from the sun orbit at a
slower speed than those closer
What does Kepler’s third law
imply about planetary
motion?
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In equal amounts of time, the lines that connect
each planet to the sun must sweep out in equal
areas. The longer the arc, the faster the planet
must move. The further the line from the sun the
slower a planet moves. Planets in perihelion will
speed up and in aphelion they will slow down.
Relate Keplar’s Second Law
to the speed of planets
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Newton
The Law of Universal
Gravitation was developed by
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smaller
According to Newton’s
second law, when the same
force acts on two bodies, the
body with the larger mass
will have the
_______acceleration
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sun
According to Newton, the
gravity of the _______ is
needed to explain planetary
orbits.
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That objects have mass that disrupt the space around
them –curving space and other objects towards that
object.
What did Einstein have to say
about Gravity?
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The third law says they each have the same
gravitational pull, butJupiter is more
massive than a Voyager, which the second
law allows Jupiter to slow a bit and the
Voyager to accelerate allow them to escape
the gravitational pull of the sun.
Using Newton’s second and third law
explain why the Voyager probes able
to pull away from Jupiter and yet
Jupiter still orbits around the sun