Question 1

The expected seasonal changes on Uranus because of its orbital and spin-axis alignments, compared to those on Earth, will be:

Accepted Answer

A) the same, because the tilt of the spin axis is the same as that of Earth. 
B) much less, because its orbit is circular. 
C) absent, because the spin axis is perpendicular to the orbital plane. 
D) very much exaggerated, because the spin axis is almost in the orbital plane. 
A) the same, because the tilt of the spin axis is the same as that of Earth. 
B) much less, because its orbit is circular. 
C) absent, because the spin axis is perpendicular to the orbital plane. 
D) very much exaggerated, because the spin axis is almost in the orbital plane.

Question 2

In what way do Uranus and Neptune differ from Jupiter and Saturn?

Accepted Answer

A) Uranus and Neptune do not have observable magnetic fields. 
B) Uranus and Neptune apparently do not have rocky cores. 
C) The atmospheric winds of Uranus and Neptune are not parallel to the equator. 
D) Hydrogen and helium make up a smaller fraction of the total mass of Uranus and Neptune. 
A) Uranus and Neptune do not have observable magnetic fields. 
B) Uranus and Neptune apparently do not have rocky cores. 
C) The atmospheric winds of Uranus and Neptune are not parallel to the equator. 
D) Hydrogen and helium make up a smaller fraction of the total mass of Uranus and Neptune.

Question 3

The particles in the rings of Uranus and Neptune are very dark. This is thought to be because they are composed partly of:

Accepted Answer

A) iron. 
B) ice particles coated with dark dust, probably carbon. 
C) methane ice, damaged by impact by electrons from the magnetosphere: radiation darkening. 
D) very dark rock. 
A) iron. 
B) ice particles coated with dark dust, probably carbon. 
C) methane ice, damaged by impact by electrons from the magnetosphere: radiation darkening. 
D) very dark rock.

Question 4

Is tidal flexing now occurring on Triton?

Accepted Answer

A) Yes, because the existence of active cryovolcanoes necessitates heating by tidal flexing. 
B) Yes, because the evaporation of nitrogen from Triton's surface suggests heating by tidal flexing. 
C) Yes, because the low crater density on Triton suggests geologic activity due to tidal flexing. 
D) No, because Triton is in a circular orbit at the present time and cannot experience tidal flexing. 
A) Yes, because the existence of active cryovolcanoes necessitates heating by tidal flexing. 
B) Yes, because the evaporation of nitrogen from Triton's surface suggests heating by tidal flexing. 
C) Yes, because the low crater density on Triton suggests geologic activity due to tidal flexing. 
D) No, because Triton is in a circular orbit at the present time and cannot experience tidal flexing.

Question 5

If the south pole of Uranus (orbital period = 84 years) was pointing as close as it ever points toward the Sun in 1986, when would the Sun next be over the equator of this planet?

Accepted Answer

A) 2070 
B) never, because of the large tilt of Uranus's axis to the perpendicular to its orbital plane 
C) 2028 
D) 2007 
A) 2070 
B) never, because of the large tilt of Uranus's axis to the perpendicular to its orbital plane 
C) 2028 
D) 2007

Question 6

The north pole of a bar magnet would be attracted to which pole of Uranus?

Accepted Answer

A) the magnetic pole above the ecliptic 
B) the magnetic pole below the ecliptic 
C) the spin axis pole above the ecliptic 
D) the spin axis pole below the ecliptic 
A) the magnetic pole above the ecliptic 
B) the magnetic pole below the ecliptic 
C) the spin axis pole above the ecliptic 
D) the spin axis pole below the ecliptic

Question 7

What method was used to determine the diameters of Pluto and its large moon, Charon?

Accepted Answer

A) observation of the sequential disappearance of the planet and the moon behind Earth's Moon in an occultation 
B) photography from a visiting spacecraft 
C) radio interferometry, with arrays of telescopes producing extremely high resolution images 
D) observation of the mutual eclipses of the planet and the moon 
A) observation of the sequential disappearance of the planet and the moon behind Earth's Moon in an occultation 
B) photography from a visiting spacecraft 
C) radio interferometry, with arrays of telescopes producing extremely high resolution images 
D) observation of the mutual eclipses of the planet and the moon

Question 8

The rings of Uranus are much more difficult to observe than the rings of Saturn. Each of the following statements is true EXCEPT ONE. Which is the exception?

Accepted Answer

A) Uranus is much farther away from the Sun than is Saturn. 
B) The rings of Uranus are much narrower. 
C) The ring particles of Uranus are made of ices and are thus transparent. 
D) Radiation darkening has greatly reduced the albedo of Uranus's ring particles. 
A) Uranus is much farther away from the Sun than is Saturn. 
B) The rings of Uranus are much narrower. 
C) The ring particles of Uranus are made of ices and are thus transparent. 
D) Radiation darkening has greatly reduced the albedo of Uranus's ring particles.

Question 9

Which of the giant jovian planets has an internal energy source that is so weak that it is masked by the energy received from the Sun so that, from evidence of excess infrared emission, it appears not to be generating energy internally?

Accepted Answer

A) Jupiter 
B) Saturn 
C) Uranus 
D) Neptune 
A) Jupiter 
B) Saturn 
C) Uranus 
D) Neptune

Question 10

Suppose a large satellite is discovered in an orbit around its planet and that the orbital period of the satellite is shorter than the rotational period of the planet around its axis. The satellite rotates to the east, and the satellite raises a tidal bulge on the planet. What can you say about the future of this satellite?

Accepted Answer

A) If this satellite also moves eastward in its orbit it will be slowed down by the attraction of the tidal bulge and will gradually move closer to the planet. 
B) If this satellite moves westward in its orbit it will be speeded up by the attraction of the tidal bulge and will gradually move closer to the planet. 
C) If this satellite also moves eastward in its orbit it will be speeded up by the attraction of the tidal bulge and will gradually move farther away from the planet. 
D) If this satellite moves westward in its orbit it will be slowed down by the attraction of the tidal bulge and will gradually move farther away from the planet. 
A) If this satellite also moves eastward in its orbit it will be slowed down by the attraction of the tidal bulge and will gradually move closer to the planet. 
B) If this satellite moves westward in its orbit it will be speeded up by the attraction of the tidal bulge and will gradually move closer to the planet. 
C) If this satellite also moves eastward in its orbit it will be speeded up by the attraction of the tidal bulge and will gradually move farther away from the planet. 
D) If this satellite moves westward in its orbit it will be slowed down by the attraction of the tidal bulge and will gradually move farther away from the planet.

Question 11

Which one of the following statements correctly describes Miranda, one of the satellites of Uranus?

Accepted Answer

A) icy surface with chaotically varied terrain 
B) rocky surface with lava lakes and several active volcanoes 
C) smooth and very dark (1% reflectivity), showing only a network of fine cracks 
D) icy, frost-covered surface with vents of rising gas visible in the northern hemisphere 
A) icy surface with chaotically varied terrain 
B) rocky surface with lava lakes and several active volcanoes 
C) smooth and very dark (1% reflectivity), showing only a network of fine cracks 
D) icy, frost-covered surface with vents of rising gas visible in the northern hemisphere

Question 12

Use Newton's form of Kepler's third law to calculate a rough estimate for the mass of Charon, Pluto's moon. Take the semimajor axis of Charon's orbit to be 19,640 km and the period to be 6.39 days. The mass of Pluto is about 1.2 x 1022 kg. This gives the mass of Charon to be about:

Accepted Answer

A) 1010 kg. 
B) 1017 kg. 
C) 1021 kg. 
D) 1023 kg. 
A) 1010 kg. 
B) 1017 kg. 
C) 1021 kg. 
D) 1023 kg.

Question 13

Most astronomers feel that there are many additional large, icy bodies beyond the orbit of Pluto. Which of the following is NOT used as a major argument in favor of this hypothesis?

Accepted Answer

A) comparison with observations of other solar systems 
B) multiple nature of the Pluto system 
C) retrograde orbit of Neptune's satellite, Triton 
D) abundance of craters observed on planets and moons in the outer solar system 
A) comparison with observations of other solar systems 
B) multiple nature of the Pluto system 
C) retrograde orbit of Neptune's satellite, Triton 
D) abundance of craters observed on planets and moons in the outer solar system

Question 14

Uranus is just visible as a naked eye object when seeing conditions are very good and when it is at:

Accepted Answer

A) superior conjunction. 
B) inferior conjunction. 
C) opposition. 
D) greatest elongation. 
A) superior conjunction. 
B) inferior conjunction. 
C) opposition. 
D) greatest elongation.

Question 15

If Uranus and Neptune had formed at their present distances from the Sun, we might expect that their properties would be quite different from what they are now. Which one of the following would NOT be a good description of Uranus and Neptune in this case?

Accepted Answer

A) They would contain a larger percentage of hydrogen and helium. 
B) They would be smaller than their present sizes. 
C) Their densities would be larger than their present values. 
D) Their compositions would include liquid metallic hydrogen. 
A) They would contain a larger percentage of hydrogen and helium. 
B) They would be smaller than their present sizes. 
C) Their densities would be larger than their present values. 
D) Their compositions would include liquid metallic hydrogen.

Question 16

The atmosphere of Uranus appears to be similar to those of Jupiter and Saturn except that it shows far less structure and patterns than they. Why is this?

Accepted Answer

A) Dust storms continually hide the features and patterns in the Uranus atmosphere. 
B) Substances that make up the clouds and patterns on Jupiter and Saturn, such as NH3 and H2O, have frozen and fallen out of Uranus's colder atmosphere. 
C) The glow of atomic auroral emissions from the polar regions of Uranus, caused by the magnetosphere, outshines the dim reflected light from the Sun, particularly because methane absorbs most the sunlight. 
D) A very high and featureless haze layer hides the clouds and patterns expected to occur on Uranus. 
A) Dust storms continually hide the features and patterns in the Uranus atmosphere. 
B) Substances that make up the clouds and patterns on Jupiter and Saturn, such as NH3 and H2O, have frozen and fallen out of Uranus's colder atmosphere. 
C) The glow of atomic auroral emissions from the polar regions of Uranus, caused by the magnetosphere, outshines the dim reflected light from the Sun, particularly because methane absorbs most the sunlight. 
D) A very high and featureless haze layer hides the clouds and patterns expected to occur on Uranus.

Question 17

The magnetic fields of Uranus and Neptune are generated by:

Accepted Answer

A) the flow of atmospheric (gaseous) methane that has been ionized by solar UV. 
B) the flow of electrically conducting molten iron in the core. 
C) the bulk flow of liquid metallic hydrogen. 
D) electrical currents in water, rendered electrically conducting by ionized molecules such as ammonia. 
A) the flow of atmospheric (gaseous) methane that has been ionized by solar UV. 
B) the flow of electrically conducting molten iron in the core. 
C) the bulk flow of liquid metallic hydrogen. 
D) electrical currents in water, rendered electrically conducting by ionized molecules such as ammonia.

Question 18

By 2006, 13 rings had been discovered around Uranus. Each of the following methods had discovered some of them, EXCEPT ONE. Which method did NOT yield discovery of some of Uranus's rings?

Accepted Answer

A) observations from Earth of the occultation of a star by the ring system 
B) direct observation by astronauts from space 
C) observation by the robotic Voyager 2 flyby mission 
D) observations from Earth's orbit by the Hubble Space Telescope 
A) observations from Earth of the occultation of a star by the ring system 
B) direct observation by astronauts from space 
C) observation by the robotic Voyager 2 flyby mission 
D) observations from Earth's orbit by the Hubble Space Telescope

Question 19

The tilt of Uranus's axis was first deduced from observed orbital motions of its moons. For the deduction of this tilt to be correct, it was necessary to assume that the moons:

Accepted Answer

A) moved in the ecliptic plane, or at least in the plane of the orbit of Uranus. 
B) passed over both north and south poles of the planet, thereby indicating the planet's spin axis. 
C) were not affected by the gravitational field of the Sun, which would force their orbits to deviate from the planet's equatorial plane. 
D) were orbiting in the equatorial plane of Uranus. 
A) moved in the ecliptic plane, or at least in the plane of the orbit of Uranus. 
B) passed over both north and south poles of the planet, thereby indicating the planet's spin axis. 
C) were not affected by the gravitational field of the Sun, which would force their orbits to deviate from the planet's equatorial plane. 
D) were orbiting in the equatorial plane of Uranus.

Question 20

What mechanism appears to have made the surfaces of many moons and the particles in the ring material of the outer planets very dark?

Accepted Answer

A) collection of large amounts of fine dust, perhaps carbon dust or soot, from interplanetary space 
B) long-term bombardment by electrons and ions in the magnetosphere: radiation darkening 
C) burning and charring of the surfaces by successive passages through the planet's atmosphere, similar to the formation of dark fusion crusts on meteorites that have hit Earth 
D) chemical changes that are caused by long-term exposure to solar ultraviolet radiation 
A) collection of large amounts of fine dust, perhaps carbon dust or soot, from interplanetary space 
B) long-term bombardment by electrons and ions in the magnetosphere: radiation darkening 
C) burning and charring of the surfaces by successive passages through the planet's atmosphere, similar to the formation of dark fusion crusts on meteorites that have hit Earth 
D) chemical changes that are caused by long-term exposure to solar ultraviolet radiation

Exam 14: Uranus, Neptune, Pluto, and the Kuiper Belt: Remote Worlds

The expected seasonal changes on Uranus because of its orbital and spin-axis alignments, compared to those on Earth, will be:

In what way do Uranus and Neptune differ from Jupiter and Saturn?

The particles in the rings of Uranus and Neptune are very dark. This is thought to be because they are composed partly of:

Is tidal flexing now occurring on Triton?

If the south pole of Uranus (orbital period = 84 years) was pointing as close as it ever points toward the Sun in 1986, when would the Sun next be over the equator of this planet?

The north pole of a bar magnet would be attracted to which pole of Uranus?

What method was used to determine the diameters of Pluto and its large moon, Charon?

The rings of Uranus are much more difficult to observe than the rings of Saturn. Each of the following statements is true EXCEPT ONE. Which is the exception?

Which of the giant jovian planets has an internal energy source that is so weak that it is masked by the energy received from the Sun so that, from evidence of excess infrared emission, it appears not to be generating energy internally?

Which one of the following statements correctly describes Miranda, one of the satellites of Uranus?

Use Newton's form of Kepler's third law to calculate a rough estimate for the mass of Charon, Pluto's moon. Take the semimajor axis of Charon's orbit to be 19,640 km and the period to be 6.39 days. The mass of Pluto is about 1.2 x 1022 kg. This gives the mass of Charon to be about:

Most astronomers feel that there are many additional large, icy bodies beyond the orbit of Pluto. Which of the following is NOT used as a major argument in favor of this hypothesis?

Uranus is just visible as a naked eye object when seeing conditions are very good and when it is at:

If Uranus and Neptune had formed at their present distances from the Sun, we might expect that their properties would be quite different from what they are now. Which one of the following would NOT be a good description of Uranus and Neptune in this case?

The atmosphere of Uranus appears to be similar to those of Jupiter and Saturn except that it shows far less structure and patterns than they. Why is this?

The magnetic fields of Uranus and Neptune are generated by:

By 2006, 13 rings had been discovered around Uranus. Each of the following methods had discovered some of them, EXCEPT ONE. Which method did NOT yield discovery of some of Uranus's rings?

The tilt of Uranus's axis was first deduced from observed orbital motions of its moons. For the deduction of this tilt to be correct, it was necessary to assume that the moons:

What mechanism appears to have made the surfaces of many moons and the particles in the ring material of the outer planets very dark?

Astronomy and the Universe

Knowing the Heavens

Eclipses and the Motion of the Moon

Gravitation and the Waltz of the Planets

The Nature of Light

Optics and Telescopes

Comparative Planetology I: Our Solar System

Comparative Planetology II: the Origin of Our Solar System

The Living Earth

Our Barren Moon

Mercury, Venus, and Mars: Terrestrial, yet Unique

Jupiter and Saturn: Lords of the Planets

Jupiter and Saturns Satellites of Fire and Ice

Asteroids, Comets, and Impacts

Our Star, the Sun

The Nature of the Stars

The Birth of Stars

Stellar Evolution: on and After the Main Sequence

Stellar Evolution: The Death of Stars

Stellar Remnants: Neutron Stars and Black Holes

Our Galaxy

Galaxies

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Cosmology: The Origin and Evolution of the Universe

Exploring the Early Universe

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Use Newton's form of Kepler's third law to calculate a rough estimate for the mass of Charon, Pluto's moon. Take the semimajor axis of Charon's orbit to be 19,640 km and the period to be 6.39 days. The mass of Pluto is about 1.2 x 10²² kg. This gives the mass of Charon to be about: