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Retrograde motion of a planet against the background stars is always


A) apparent motion of the planet away from Earth.
B) movement northward away from the ecliptic plane.
C) movement from west to east.
D) movement from east to west.

E) A) and B)
F) None of the above

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Why were Newton's three laws so important to astronomy?


A) Newton's laws showed that acceleration always results from a change in velocity.
B) Newton's laws showed why objects released from rest always fall to the ground.
C) Newton's laws showed that planets can move around the Sun by themselves forever, without coming to rest.
D) Newton's laws provided a physical basis that did not conflict with the Bible, Aristotle, or Plato.

E) A) and D)
F) A) and C)

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Suppose that an object has a certain speed, kinetic energy, and momentum. If the object's speed increases until it has 4 times the kinetic energy that it had before, then its momentum is


A) 2 times greater than before.
B) unchanged.
C) 16 times greater than before.
D) 4 times greater than before.

E) B) and D)
F) A) and B)

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The MOST serious flaw in the solar system model of Copernicus was


A) Earth was at the center of the system.
B) the orbits were circular rather than elliptical.
C) it failed to take precession into account.
D) it failed to take retrograde motion into account.

E) A) and B)
F) None of the above

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What is the difference between the synodic and sidereal periods of a planet?


A) The synodic period refers to the planet's period with respect to Earth's motion, whereas the sidereal period is the true period with respect to the background stars.
B) There is no difference; they are one and the same time period. The synodic period is the name used in the geocentric theory, whereas the sidereal period is the name used in the heliocentric theory.
C) The synodic period refers to the planet's motion with respect to the background stars, whereas the sidereal period is the true period with respect to Earth's motion.
D) The synodic period refers to the planet's rotation around its axis, whereas the sidereal period is the time for one orbit.

E) B) and C)
F) A) and D)

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The time from one inferior conjunction of Mercury to the next inferior conjunction of Mercury is 116 days. The time from one superior conjunction of Mercury to the next superior conjunction is


A) 58 days.
B) 116 days.
C) 232 days.
D) impossible. Mercury does not experience superior conjunction.

E) A) and C)
F) C) and D)

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The contribution of Copernicus to the development of astronomy was a mathematical model for a


A) heliocentric cosmology in which the planets move in circular orbits.
B) solar system in which the planets move under the gravitational influence of the Sun.
C) heliocentric cosmology in which the planets move in elliptical orbits.
D) geocentric cosmology in which the planets move in circular epicycles.

E) B) and D)
F) B) and C)

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Venus shows changes in angular size and also shows phases similar to the phases of the Moon. According to Galileo, who first saw the phases, these observations showed that Venus


A) orbits Earth in an elliptical orbit.
B) moves in epicycles.
C) does not rotate on its axis.
D) orbits the Sun.

E) A) and C)
F) All of the above

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Suppose that, at the same time on the same night, an astronomer sees two supernovas (exploding stars) explode in the night sky. If one is in the Andromeda Galaxy, 2 million light-years away from us, and the other is in the galaxy M82, 6 million light-years away from Earth, which of these statements concerning the actual explosion times of these supernovas is correct?


A) It is not possible to determine which star actually exploded first because both stars are so far away.
B) The supernova in the Andromeda Galaxy actually occurred after the one in M82.
C) Both stars exploded at the same time because the explosions were observed at the same time.
D) The supernova in the Andromeda Galaxy actually occurred before the one in M82.

E) B) and C)
F) A) and C)

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Which concept in Newton's mechanics provides an answer to the question: Why don't the planets fall into the Sun?


A) conservation of energy
B) conservation of mass
C) conservation of momentum
D) conservation of angular momentum

E) B) and C)
F) A) and D)

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The eccentricity of a planet's orbit describes


A) the tilt of the planet's spin axis with respect to its orbital plane.
B) its shape compared to that of a circle.
C) its motion at any specific point in its orbit as seen from Earth, that is, whether direct, retrograde, or stationary.
D) its tilt with respect to the plane of Earth's orbit (the ecliptic plane) .

E) A) and D)
F) A) and C)

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According to the Ptolemaic model of the solar system, during retrograde motion a planet would be


A) at varying distances from Earth, sometimes closer and sometimes farther away than the average distance.
B) farther away from Earth than average.
C) closer to Earth than average.
D) always at the same distance from Earth because the planet orbits Earth in a circle in this model.

E) B) and D)
F) A) and D)

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Retrograde motion was a major source of difficulty in designing a theoretical model of the solar system. What is the explanation for retrograde motion?


A) The planets actually stop and reverse direction in their orbits.
B) The planets move not in uniform circular motion about the Sun but rather in circular orbits (epicycles) about points which themselves move about the Sun in circular orbits.
C) Retrograde motion is an apparent motion of other planets, which we observe only because we are viewing their motion from Earth, itself in motion around the Sun.
D) Retrograde motion is an apparent motion caused by the precession of Earth's rotation axis.

E) C) and D)
F) A) and B)

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The angular diameter of Venus appears largest when its phase is


A) crescent.
B) half.
C) gibbous.
D) full.

E) C) and D)
F) B) and C)

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Not counting Earth, the number of planets known to the ancients was


A) 4.
B) 5.
C) 7.
D) 8.

E) A) and B)
F) C) and D)

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If two massive bodies, initially held at rest in space, are released, then they will begin to


A) move away from each other with constant acceleration.
B) move toward one another.
C) move in elliptical orbits around one another.
D) orbit one another in circles.

E) A) and D)
F) All of the above

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An inferior planet is farthest from Earth when it is at


A) superior conjunction.
B) opposition.
C) inferior conjunction.
D) greatest elongation.

E) C) and D)
F) B) and C)

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Newton's second law of motion states that


A) a force is always required to keep an object in motion.
B) a body acted on by a net force will accelerate continually while the force is applied.
C) objects orbiting the Sun always move in elliptical orbits.
D) a body acted on by a force will move at a constant speed while the force is applied.

E) A) and B)
F) A) and C)

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Before the invention of the telescope, the known planets were


A) Mercury, Venus, Mars, Jupiter, and Saturn.
B) Mercury, Venus, Mars, Jupiter, and Uranus.
C) Jupiter, Venus, Neptune, Mars, and Saturn.
D) Mars, Neptune, Jupiter, Mercury, and Venus.

E) None of the above
F) A) and B)

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Place these events in chronological order, from earliest to latest.


A) Copernicus's heliocentric model, Kepler's third law, Galileo's discovery of Jupiter's moons
B) Kepler's third law, Copernicus's heliocentric model, Galileo's discovery of Jupiter's moons
C) Copernicus's heliocentric model, Galileo's discovery of Jupiter's moons, Kepler's third law
D) Kepler's third law, Galileo's discovery of Jupiter's moons, Copernicus's heliocentric model

E) B) and D)
F) A) and D)

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