Use these questions to test your understanding. If you get them wrong, you will be linked back to the relevant part of the notes.
Be sure you study them thoroughly (don't just get a quick fix for your mistake) so your overall understanding is improved.
1. Theories of the solar system were severely challenged for centuries by
a. errors in predicting the motions of the planets
c. changes in brightness of the planets as they get closer or farther away from the earth
d. why the planets all seemed to move along the same zone in the sky
2. Two planets are observed going around a star. Planet Xoron has an orbital period that is twice as long as Planet Krypton. Which planet has a shorter average orbital radius?
a. Xoron b. Krypton c. They will both be the same d. Not enough information to tell
3. Kepler's "music of the spheres" theory
a. was a hopelessly bad fit to the planetary orbital periods
b. was an impressively good fit to the motions of the stars
c. was an impressively good fit to the planetary orbital periods
d. was an impressively good fit to the eccentricity of the orbits of the planets
e. related the day to the month and year
4. Copernicus' theory for the solar system
a. made much more accurate predictions than previous theories
b. was much simpler than previous theories
c. was obviously a big improvement over previous theories
d. was attractive initially for aesthetic reasons only
e. introduced new physical principles to understand the motions of the planets
5. Suppose two comets, comet A and comet B, were orbiting the sun, having the same average
orbital radii. If comet A had a higher orbital eccentricity than comet B, which comet would, during
some portion of its orbit, have the higher orbital speed?
a. A b. B c. both would be the same d. impossible to tell
6. Copernicus developed his theory of the solar system because
a. he wanted to try new orbital shapes to improve the predictions
b. he just wanted to try something different
c. he was disturbed by the complexities being used to fit the planet motions
d. he had a mystical vision one night that the sun was at the center of the solar system
e. his measurements of the sizes of the earth, moon, and sun argued that the sun was at the center
7. During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space?
a. The Earth and Mars are getting closer together.
c. Earth and Mars are on opposite sides of the Sun.
d. Earth is catching up with and passing by Mars in their respective orbits.
e. Mars is going around on an epicycle
8. The period-radius relationship analogous to Kepler's third law but for the wheel of your bicycle would be
a. the period of revolution goes in proportion to the radius
b. the period of revolution goes in proportion to the square of the radius
c. the square of the period of revolution goes as the cube of the radius
d. the period of revolution is independent of the radius
e. there is no fixed relation between the period of revolution and the radius
9. Kepler's three laws of planetary motion did NOT
a. provide an underlying physical cause for the planetary motions
b. correctly predict the speed with which a planet goes at different places around its orbit
c. correctly state the shapes of the orbits of the planets
10. Parallax was difficult to observe because
a. astronomers did not know where to look
b. the distances to the nearest stars are huge compared with the orbit of the earth
c. astronomers measured the wrong stars
d. parallax is only obvious in earth-centered solar systems
e. it is just one of those things that no one thought was important
11. Tycho showed that comets
a. interact with the atmosphere of the earth
c. are part of the solar system and not associated only with the earth
d. are not the cause of plagues, and other troubles on earth
e. move on orbits shaped differently from those of the planets
12. Kepler's great breakthrough in explaining the motions of the planets came because
a. For the first time, he put the sun at the center of the system
c. he realized that gravity could hold the planets in their orbits
d. he was the first to use mathematics to calculate planet orbits
e. he realized that the planet orbits are ellipses, not combinations of circles