The Outer Planets - Quiz 9

1. The low average densities of Jupiter and Saturn compared with the Earth suggests
A).. they are hollow.
B)..their gravitational attraction has compressed their cores into a rare form of iron.
C).. they contain large quantities of light elements, such as hydrogen and helium.
D).. they are very hot.
E)..volcanic eruptions have ejected all the iron that was originally in their cores.

2. 2.What makes some astronomers think that Uranus was hit by a large body early in its history?
A)...It goes around the Sun in a direction opposite to the other planets.
B)... Its rotation axis has such a large tilt with respect to its orbit.
C)...Its composition is so different from those of Neptune, Jupiter, and Saturn.
D)...It has no moons.
E)...All of the above.

3. Why would it be foolish to send astronauts to land on Jupiter?
A)... It has no solid surface for them to land on.
B)... Its clouds are so hot that any spacecraft getting near it would burn up.
C)...Its gravitational attraction is so weak that they would float off.
D)...All of the above.
E)... The idea is perfectly reasonable.

4. What is the Roche limit?
A)... The mass a planet must exceed to have satellites.
B)... The smallest mass a planet can have and still be composed mainly of hydrogen.
C)... The greatest distance from a planet that its satellites can orbit without falling into the Sun.
D)... The distance at which a moon held together by gravity will be broken apart by the planet's gravitational attraction.
E)... the distance astronomers can see into a planet's clouds.

5. Astronomers think that the inner core of Jupiter is composed mainly of
A)... hydrogen.
B)... helium.
C)... uranium.
D)... rock and iron.
E)... water.

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