1. The center, or fixed point, of the Greek model of the universe was
A.the center of the galaxy.
B.close to Earth's center.
C.a point midway between Earth and Sun.
D.the Sun's center.


2. When observing planetary motions from Earth, the phrase "direct motion" refers to
A.the motion of the planet directly toward or away from Earth at certain parts of the planet's orbit.
B.a slow eastward motion of the planet from night to night against the background stars.
C.a slow westward motion of the planet from night to night against the background stars.
D.the apparent westward motion of the planet (along with the Sun, Moon, and stars) across the sky due to the rotation of Earth.


3. When observing planetary motions from Earth, the phrase "retrograde motion" refers to
A.motion of the planet away from Earth during part of its orbit.
B.a slow eastward motion of the planet from night to night against the background stars.
C.the apparent westward motion of the planet (along with the Sun, Moon, and stars) across the sky due to the rotation of Earth.
D.a slow westward motion of the planet from night to night against the background stars.


4. In the geocentric model of the solar system developed by Ptolemy, planets move
A.in circular epicycles around the Sun while the Sun moves in a circular orbit around Earth.
B.at constant speeds in circular orbits around Earth.
C.with varying speeds in elliptical orbits around Earth.
D.in circular epicycles while the centers of the epicycles move in circular orbits around the Earth.


5. The purpose of describing planetary orbits in terms of epicycles and deferents was to account for the
A.generally eastward motion of a planet compared to background stars while the whole sky appeared to move westward.
B.variation of brightness of a planet with time.
C.difference between the sidereal period and the synodic period of a planet.
D.pattern of direct and retrograde motion of a planet as it moved slowly against the background of stars.


6. Retrograde motion of a planet when viewed from Earth is caused by
A.the relative motions of Sun and planet.
B.its elliptical orbital path.
C.the relative motions of Earth and planet.
D.the inclination of its orbit to the ecliptic plane.


7. The early Copernican system for planetary motions is
A.Earth-centered, with planets, the Sun, and the stars moving in perfect circles.
B.Earth-centered, with planets moving in epicycle patterns around Earth.
C.Sun-centered, with planets moving in perfect circles around the Sun.
D.Sun-centered, with planets moving in elliptical orbits, the Sun being at one focus of the ellipse.


8. Which of the following planets passes between the Earth and the Sun?
A.Pluto
B.Mars
C.Jupiter
D.Venus


9. The sidereal period of a planet is defined as the time between
A.two successive passages of the planet in front of a particular point in the sky (e.g., a star) as seen from Earth.
B.two successive identical configurations (e.g., opposition to opposition).
C.two successive passages of the planet in front of a particular point in the sky (e.g., a star) as seen from the Sun.
D.two successive greatest elongations (e.g., greatest western elongation to greatest eastern elongation).


10. The synodic period of a planet is defined as the time between
A.two successive passages of the planet in front of a particular point in the sky (e.g., a star) as seen from Earth.
B.two successive identical configurations (e.g., opposition to opposition).
C.two successive passages of the planet in front of a particular point in the sky (e.g., a star) as seen from the Sun.
D.two successive greatest elongations (e.g., greatest western elongation to greatest eastern elongation).


11. The greatest inaccuracy in Copernicus' theory of the solar system was that he
A.placed the planets in circular orbits.
B.placed the planets on epicycles, the centers of which followed orbits around Earth.
C.did not allow for retrograde motion.
D.assumed that the planets move in elliptical orbits with constant speeds rather than variable speeds.


12. One of the major contributions of Galileo to the development of modern astronomy was to
A.discover the satellites (moons) of Jupiter.
B.prove that planetary orbits were ellipses.
C.use parallax to prove that Earth moved around the Sun.
D.develop the first mathematical heliocentric model of the solar system.


13. The major contribution of Johannes Kepler to the development of modern astronomy was to
A.develop the first mathematical heliocentric model of the solar system.
B.observe the satellites (moons) of Jupiter.
C.use parallax to prove that Earth moves around the Sun.
D.prove that planetary orbits are ellipses.


14. Kepler's laws describe the
A.motions of the planets around the Sun.
B.motion of the spin axis of Earth over long time periods.
C.motions of the planets around Earth.
D.motion of the Moon around the Sun.


15. Kepler's second law states that a line joining a planet to the Sun
A.sweeps through equal angles in equal times.
B.points in the same direction at all times.
C.sweeps out equal areas in equal times.
D.moves equal distances along the planet's orbit in equal times.


16. Which of the following statements is true, according to Kepler's third law?
A.The smaller the orbit, the longer it takes for the planet to complete one revolution.
B.The smaller the radius of a planet, the more rapidly it rotates on its axis.
C.The larger the orbit, the longer it takes for the planet to complete one revolution.
D.The time to complete one revolution of its orbit depends on the size or radius of the planet.


17. What was the MOST IMPORTANT difference in development between Isaac Newton's theory of planetary motion and that of Johannes Kepler?
A.Newton lived in a freer political climate, whereas Kepler risked house arrest if his theory opposed the Bible or Aristotle.
B.Newton lived in England, which is famous for clear skies, whereas Kepler lived on the Continent, which is notorious for bad weather.
C.Newton developed his theory from basic physical assumptions, whereas Kepler simply adjusted his theory to fit the data.
D.Newton based his theory on accurate telescopic observations, whereas Kepler used observations made by eye.


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


19. In Newton's law of universal gravitation, F = GMm/R2, which defines the force between Earth with mass M and an orbiting satellite of mass m at a distance R from Earth, G
A.is variable, depending on the masses of the two objects.
B.depends on the material occupying the space between the two objects.
C.is a constant, throughout all measured space and time.
D.depends on the speed of motion of the satellite.


20. The force of gravity between two objects is proportional to the
A.difference of their masses.
B.product of their masses.
C.ratio of their masses.
D.sum of their masses.


21. As a spacecraft such as Voyager 2 moves away from the Sun, the gravitational force on it F varies with distance R from the Sun in which mathematical way? (µ means "proportional to.")
A.F µ 1/R
B.F µ R
C.F = constant, independent of distance
D.F µ 1/R2



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