The Formation of Gas Planets
- What is the main purpose of the lecture?
- A. To describe two new theories about the formation of rocky planets.
- B. To discuss competing theories about the formation of gas planets.
- C. To compare the composition of Jupiter, Saturn, Uranus, and Neptune.
- D. To explain why young stars are often surrounded by disks of gas and dust.
- Why does the professor review the formation of rocky planets?
- A. To contrast it with the formation of the Sun.
- B. To correct a common misunderstanding about accretion.
- C. To use the information as the basis for another topic of discussion.
- D. To introduce recent discoveries about rocky planets in other solar systems.
- What point does the professor emphasize when he mentions water and ammonia?
- A. Solid forms of water and ammonia may have contributed to the formation of the gas giants.
- B. Water and ammonia were not common substances in the outer accretion disk.
- C. Water and ammonia are pulled in by the gravity of proto-planets more readily than other substances are.
- D. Most substances found in the core of rocky planets are also found in the core of gas planets.
- According to the professor, what could have occurred when a proto-planet in the outer accretion disk reached a mass of five to ten Earths?
- A. It started to shed grains of rock and metal into the solar system.
- B. Its gravity began to pull in huge amounts of the surrounding gas.
- C. Its gravity caused clumps to form in the surrounding gas.
- D. It collided with smaller proto-planets.
- According to the professor, what are TWO claims of the disk-instability theory?
[CHOOSE 2 ANSWERS]
- A. Gas planet formation did not begin with a solid core.
- B. Gas planets cannot form in extremely cold temperatures.
- C. Gas planet formation can occur anywhere in the accretion disk.
- D. Gas planets form over a relatively short time.
- Which is right about the professor’s opinion about the disk-instability theory?
- A. It differs from the core-accretion theory in relatively insignificant ways.
- B. It does not take into account the amount of time needed for gas planets to form.
- C. It is more applicable to star formation than the core-accretion theory is.
- D. Solid particles are believed to own a small proportion of the outer accretion disk.
B C A B AD D