TPO38L4 The Formation of Gas Planets (Astronomy)



1.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.


2.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.


3.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 protoplanets 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.


4.According to the professor, what could have occurred when a protoplanet 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 protoplanets.


5.According to the professor, what are two claims of the disk-instability theory?

[Click on 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. 


6.Which is 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. It is more plausible than the core-accretion theory for the formation of gas planets.


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