Listen to part of a lecture in an astronomy class.
1. What is the lecture mainly about?
- A. The orbits of comets.
- B. Unique characteristics of a famous comet.
- C. The structure of comets.
- D. The origin and life cycle of comets.
2. According to the professor, what happens as a comet approaches the Sun?
[CHOOSE 2 ANSWERS]
- A. Its nucleus loses some material.
- B. Its core becomes brighter.
- C. It moves faster.
- D. It absorbs gases from the Sun.
3. Why does the professor emphasize the amount of time Hailey’s Comet is beyond the orbit of Jupiter?
- A. To account for the comet’s composition of ice and dust.
- B. To show the effect of Jupiter’s gravity on the comet’s orbit.
- C. To argue that the comet’s orbit should not be considered periodic.
- D. To explain why the comet is not visible from Earth very often.
4. What is the professor imply about the history of Hailey’s Comet?
- A. Hailey’s Comet did not always have the same orbit it has now.
- B. Hailey’s Comet used to be much smaller than it is now.
- C. Hailey’s Comet has always had the same orbit that it has now.
- D. Hailey’s Comet is much younger than the rest of the solar system.
5. What is the professor’s opinion about the name “parabolic-orbit comets”?
- A. It is not widely accepted among astronomers.
- B. It is probably not strictly accurate.
- C. It is not a term that the students need to learn.
- D. It will probably be replaced soon with a new name.
6. According to the professor, what can change a parabolic-orbit into a periodic-orbit comet?
- A. The loss of some of the comet’s material.
- B. The force of escaping gases.
- C. The gravitational influence of a planet.
- D. Energy from the Sun.