Astr 104, Spring 2008 – Quiz 3

1. Why did prehistoric astronomical sites have circular stone arrangements?
a. To mark directions along the horizon where astronomical objects rise and set.
b. Each of the stones indicated one of the constellations of the Zodiac.
c. The circle and the stones symbolized the Sun and its rays of light.
d. To represent artistically the celestial sphere and the stars' positions.

2. Aristotle concluded that the Earth did not revolve around the Sun because
a. He carefully observed the motion of planets over long times.
b. He could not feel the Earth's motion or see star parallax.
c. He had read about Copernicus' and Kepler's work.
d. He was following religious teachings.

3. How did geocentric models (Ptolemy's model) explain Mars' retrograde motion?
a. Using the concept of parallax.
b. Using the concept of epicyles.
c. Using the gravitational attraction of other planets.
d. They assumed it had been hit by an asteroid.

4. Is Mars in retrograde motion right now?
a. No, Mars never moves with retrograde motion.
b. No, it has just recently finished a period of retrograde motion.
c. Yes, Mars will be in retrograde motion for the next six months.
d. Yes, Mars is a planet that always moves in retrograde motion.

5. What do we mean when we say that a planet is in "retrograde motion"?