Question 1

Mercury is always much closer to the Sun than Venus is, and yet it never appears brighter than Venus, even at maximum brightness. Explain.

Accepted Answer

A)  We never see more than a small fraction of Mercury's illuminated surface because of its orbital path relative to that of Earth; hence it always appears dark. 
B)  Mercury has a thick atmosphere that impedes reflection from its surface and hence appears dark. 
C)  Mercury has a high albedo, or reflectivity, but it is very small and hence appears relatively dark. 
D)  Mercury is small, has a dark surface, and has no reflecting clouds. 
A)  We never see more than a small fraction of Mercury's illuminated surface because of its orbital path relative to that of Earth; hence it always appears dark. 
B)  Mercury has a thick atmosphere that impedes reflection from its surface and hence appears dark. 
C)  Mercury has a high albedo, or reflectivity, but it is very small and hence appears relatively dark. 
D)  Mercury is small, has a dark surface, and has no reflecting clouds.

Question 2

The reddish color of Mars is probably due to

Accepted Answer

A)  the glow from the very high temperature surface on the sunlit parts of Mars. 
B)  iron oxides such as rust. 
C)  vegetation turning red in the Martian autumn. 
D)  sulfur compounds thrown out by active volcanoes. 
A)  the glow from the very high temperature surface on the sunlit parts of Mars. 
B)  iron oxides such as rust. 
C)  vegetation turning red in the Martian autumn. 
D)  sulfur compounds thrown out by active volcanoes.

Question 3

When Venus is seen at inferior conjunction, a ring of light is seen around it. What does this ring tell astronomers about Venus?

Accepted Answer

A)  The Venusian atmosphere is so hot that it glows, even on its dark side. 
B)  Venus has auroral displays like those on Earth, which extend over the whole planet. 
C)  Venus is very massive because the gravitational field of Venus is sufficient to bend sunlight around the planet toward Earth. 
D)  Venus has a thick atmosphere that scatters sunlight toward Earth. 
A)  The Venusian atmosphere is so hot that it glows, even on its dark side. 
B)  Venus has auroral displays like those on Earth, which extend over the whole planet. 
C)  Venus is very massive because the gravitational field of Venus is sufficient to bend sunlight around the planet toward Earth. 
D)  Venus has a thick atmosphere that scatters sunlight toward Earth.

Question 4

Observations of tectonic activity differ on Venus and on Earth. A reasonable explanation is that on Venus

Accepted Answer

A)  the crust appears to be thicker and is therefore too rigid to break up into moving plates. 
B)  the surface is broken into only two plates, divided by a line at an angle to the equator. 
C)  the crust appears to be thinner and weaker and cannot support the creation and motion of solid plates. 
D)  mantle convection appears to be more vigorous and has broken the lithosphere into a multitude of small plates instead of a few large ones. 
A)  the crust appears to be thicker and is therefore too rigid to break up into moving plates. 
B)  the surface is broken into only two plates, divided by a line at an angle to the equator. 
C)  the crust appears to be thinner and weaker and cannot support the creation and motion of solid plates. 
D)  mantle convection appears to be more vigorous and has broken the lithosphere into a multitude of small plates instead of a few large ones.

Question 5

Which of these is true of Mars?

Accepted Answer

A)  Linear canals, apparently built to carry water for irrigation, crisscross the planet. 
B)  Water can be seen in the bottoms of river valleys on spacecraft photographs. 
C)  Mars has dry riverbeds but no liquid water on its surface at the present time. 
D)  There is no evidence of water ever having been on Mars. 
A)  Linear canals, apparently built to carry water for irrigation, crisscross the planet. 
B)  Water can be seen in the bottoms of river valleys on spacecraft photographs. 
C)  Mars has dry riverbeds but no liquid water on its surface at the present time. 
D)  There is no evidence of water ever having been on Mars.

Question 6

There are many reasons why a multiday hiking trip on foot across Aphrodite Terra on Venus would not be advisable, at least not without suitable protection. Which of these conditions would NOT be a concern?

Accepted Answer

A)  corrosive mists in the atmosphere 
B)  very cold nighttime temperatures 
C)  predominantly carbon dioxide atmosphere 
D)  no water 
A)  corrosive mists in the atmosphere 
B)  very cold nighttime temperatures 
C)  predominantly carbon dioxide atmosphere 
D)  no water

Question 7

Mercury's atmosphere consists mostly of

Accepted Answer

A)  sulfur dioxide and hydrogen sulfide from volcanoes. 
B)  carbon dioxide. 
C)  nitrogen and oxygen, with traces of carbon dioxide and argon. 
D)  hydrogen, helium, potassium, sodium, and oxygen. 
A)  sulfur dioxide and hydrogen sulfide from volcanoes. 
B)  carbon dioxide. 
C)  nitrogen and oxygen, with traces of carbon dioxide and argon. 
D)  hydrogen, helium, potassium, sodium, and oxygen.

Question 8

Venus appears to be very bright as viewed from Earth at certain times because

Accepted Answer

A)  its rocky surface is shiny, like the surface of new volcanic lava. 
B)  it is glowing from the heat of its surface, where the temperature is 750 K. 
C)  it is covered by very reflective clouds. 
D)  even though its surface is very dark, it is relatively close to the Sun. 
A)  its rocky surface is shiny, like the surface of new volcanic lava. 
B)  it is glowing from the heat of its surface, where the temperature is 750 K. 
C)  it is covered by very reflective clouds. 
D)  even though its surface is very dark, it is relatively close to the Sun.

Question 9

Which of these correctly explains why Venus has a higher surface temperature than Mercury.

Accepted Answer

A)  Venus is closer to the Sun than Mercury is. 
B)  Venus has a dense atmosphere of carbon dioxide. 
C)  Venus is still contracting gravitationally and thus giving out more radiant energy than it receives. 
D)  Venus has a higher albedo (reflectance) than Mercury. 
A)  Venus is closer to the Sun than Mercury is. 
B)  Venus has a dense atmosphere of carbon dioxide. 
C)  Venus is still contracting gravitationally and thus giving out more radiant energy than it receives. 
D)  Venus has a higher albedo (reflectance) than Mercury.

Question 10

What is the major difference between Mariner 10 and MESSENGER?

Accepted Answer

A)  Mariner 10 flew past Mercury several times. MESSENGER went into orbit around the planet. 
B)  MESSENGER made a soft landing on Mercury, but Mariner 10 only flew by. 
C)  The two spacecraft were essentially identical, except that Mariner 10 landed on the daylight side of the planet and MESSENGER landed on the night side. 
D)  Mariner 10 was a failed mission. It crashed into Mercury. MESSENGER conducted a successful flyby. 
A)  Mariner 10 flew past Mercury several times. MESSENGER went into orbit around the planet. 
B)  MESSENGER made a soft landing on Mercury, but Mariner 10 only flew by. 
C)  The two spacecraft were essentially identical, except that Mariner 10 landed on the daylight side of the planet and MESSENGER landed on the night side. 
D)  Mariner 10 was a failed mission. It crashed into Mercury. MESSENGER conducted a successful flyby.

Question 11

Viking 1 and Viking 2, the planet-exploring spacecraft, were sent to which planet?

Accepted Answer

A)  Mars 
B)  Jupiter 
C)  Venus 
D)  Mercury 
A)  Mars 
B)  Jupiter 
C)  Venus 
D)  Mercury

Question 12

The MOST likely source for the sulfur compounds in the clouds above the surface of Venus appears to be

Accepted Answer

A)  intense wind storms that have carried surface dust high into the atmosphere. 
B)  meteoritic material that burned up as it fell into the Venusian atmosphere. 
C)  recent eruptions of volcanoes, spewing gases and dust high into the atmosphere. 
D)  the solar wind, having been captured by the intense magnetic field of the planet. 
A)  intense wind storms that have carried surface dust high into the atmosphere. 
B)  meteoritic material that burned up as it fell into the Venusian atmosphere. 
C)  recent eruptions of volcanoes, spewing gases and dust high into the atmosphere. 
D)  the solar wind, having been captured by the intense magnetic field of the planet.

Question 13

Both Mercury and Earth have global magnetic fields. Compared to Earth, which feature is Mercury known to lack that is thought necessary for generating a STRONG field?

Accepted Answer

A)  Mercury does not lack any such feature. 
B)  large iron core 
C)  rapid planetary rotation 
D)  molten iron core 
A)  Mercury does not lack any such feature. 
B)  large iron core 
C)  rapid planetary rotation 
D)  molten iron core

Question 14

The highest temperature in the Venusian atmosphere occurs where?

Accepted Answer

A)  in the clear atmospheric layers below the cloud level, at an altitude of about 30 km 
B)  at the planet's surface 
C)  at the height of the thickest clouds, 48-52 km, where infrared absorption is highest 
D)  at the cloud tops, which are heated by sunlight 
A)  in the clear atmospheric layers below the cloud level, at an altitude of about 30 km 
B)  at the planet's surface 
C)  at the height of the thickest clouds, 48-52 km, where infrared absorption is highest 
D)  at the cloud tops, which are heated by sunlight

Question 15

Why do planetary scientists believe there are active volcanoes on Venus?

Accepted Answer

A)  Images from the Russian Venera lander show a volcanic plume. 
B)  Radar evidence from the Magellan orbiter shows fresh basalt on the surface. 
C)  Radar mapping has indicated a boundary line between tectonic plates, and such boundaries always include volcanic activity. 
D)  The amount of short-lived sulfur compounds detected in the atmosphere of Venus implies regular replenishment. 
A)  Images from the Russian Venera lander show a volcanic plume. 
B)  Radar evidence from the Magellan orbiter shows fresh basalt on the surface. 
C)  Radar mapping has indicated a boundary line between tectonic plates, and such boundaries always include volcanic activity. 
D)  The amount of short-lived sulfur compounds detected in the atmosphere of Venus implies regular replenishment.

Question 16

Rover Opportunity discovered Martian rocks with polygon-shaped cracks. One theory is that an impact released water from the Martian soil to flood these rocks. Water seeped into the rocks, froze, and caused the cracks. This explanation requires large amounts of water for several reasons. Which of these is NOT one of these reasons?

Accepted Answer

A)  The surface temperature on Mars is always below the freezing point of water. 
B)  Much of the water thus liberated would be vaporized by the impact. 
C)  Liquid water on the surface of Mars would vaporize because of the low pressure. 
D)  Such rocks have been discovered at widespread locations on Mars. 
A)  The surface temperature on Mars is always below the freezing point of water. 
B)  Much of the water thus liberated would be vaporized by the impact. 
C)  Liquid water on the surface of Mars would vaporize because of the low pressure. 
D)  Such rocks have been discovered at widespread locations on Mars.

Question 17

The moons of Mars are

Accepted Answer

A)  ice-covered, approximately spherical, but flattened by rapid rotation. 
B)  spherical and have active volcanoes on their surfaces. 
C)  spherical and smooth-surfaced (no visible craters or volcanoes). 
D)  irregularly shaped, cratered, and grooved. 
A)  ice-covered, approximately spherical, but flattened by rapid rotation. 
B)  spherical and have active volcanoes on their surfaces. 
C)  spherical and smooth-surfaced (no visible craters or volcanoes). 
D)  irregularly shaped, cratered, and grooved.

Question 18

Which of these features has NOT been seen or detected on Mars?

Accepted Answer

A)  polar ice caps 
B)  dust storms 
C)  active volcanoes 
D)  erosion of surface features 
A)  polar ice caps 
B)  dust storms 
C)  active volcanoes 
D)  erosion of surface features

Question 19

The reason that very few impact craters are seen on Venus compared with the Moon is believed to be that

Accepted Answer

A)  Venus formed closer to the Sun than the Moon did, where the cratering rate was much lower. 
B)  due to rainfall and wind, all but the most recent craters have eroded away. 
C)  lava flows and surface melting have covered all but the most recent craters. 
D)  the surface of Venus has been subducted down into the planet several times in its history, thereby removing evidence of impacts. 
A)  Venus formed closer to the Sun than the Moon did, where the cratering rate was much lower. 
B)  due to rainfall and wind, all but the most recent craters have eroded away. 
C)  lava flows and surface melting have covered all but the most recent craters. 
D)  the surface of Venus has been subducted down into the planet several times in its history, thereby removing evidence of impacts.

Question 20

Observers in the nineteenth century reported seeing many straight-line features crisscrossing the surface of Mars and interpreted them to be canals constructed by intelligent beings. What is the MOST likely present-day explanation for these observations?

Accepted Answer

A)  The lines were rifts in the Martian surface at the boundaries of geological tectonic plates. 
B)  The lines were linear, stationary cloud formations (mountain lee wave clouds) and weather fronts moving around with the planet. 
C)  The lines were optical illusions caused by vague shadings on the planet's surface. 
D)  The lines were groups of dark volcanoes similar to those of the Hawaiian Islands on Earth. 
A)  The lines were rifts in the Martian surface at the boundaries of geological tectonic plates. 
B)  The lines were linear, stationary cloud formations (mountain lee wave clouds) and weather fronts moving around with the planet. 
C)  The lines were optical illusions caused by vague shadings on the planet's surface. 
D)  The lines were groups of dark volcanoes similar to those of the Hawaiian Islands on Earth.

Mercury is always much closer to the Sun than Venus is, and yet it never appears brighter than Venus, even at maximum brightness. Explain.

The reddish color of Mars is probably due to

When Venus is seen at inferior conjunction, a ring of light is seen around it. What does this ring tell astronomers about Venus?

Observations of tectonic activity differ on Venus and on Earth. A reasonable explanation is that on Venus

Which of these is true of Mars?

There are many reasons why a multiday hiking trip on foot across Aphrodite Terra on Venus would not be advisable, at least not without suitable protection. Which of these conditions would NOT be a concern?

Mercury's atmosphere consists mostly of

Venus appears to be very bright as viewed from Earth at certain times because

Which of these correctly explains why Venus has a higher surface temperature than Mercury.

What is the major difference between Mariner 10 and MESSENGER?

Viking 1 and Viking 2, the planet-exploring spacecraft, were sent to which planet?

The MOST likely source for the sulfur compounds in the clouds above the surface of Venus appears to be

Both Mercury and Earth have global magnetic fields. Compared to Earth, which feature is Mercury known to lack that is thought necessary for generating a STRONG field?

The highest temperature in the Venusian atmosphere occurs where?

Why do planetary scientists believe there are active volcanoes on Venus?

The moons of Mars are

Which of these features has NOT been seen or detected on Mars?

The reason that very few impact craters are seen on Venus compared with the Moon is believed to be that

Observers in the nineteenth century reported seeing many straight-line features crisscrossing the surface of Mars and interpreted them to be canals constructed by intelligent beings. What is the MOST likely present-day explanation for these observations?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Lives of Stars From Birth Through Middle Age

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters

Exam 8: The Other Terrestrial Planets

Mercury is always much closer to the Sun than Venus is, and yet it never appears brighter than Venus, even at maximum brightness. Explain.

The reddish color of Mars is probably due to

When Venus is seen at inferior conjunction, a ring of light is seen around it. What does this ring tell astronomers about Venus?

Observations of tectonic activity differ on Venus and on Earth. A reasonable explanation is that on Venus

Which of these is true of Mars?

There are many reasons why a multiday hiking trip on foot across Aphrodite Terra on Venus would not be advisable, at least not without suitable protection. Which of these conditions would NOT be a concern?

Mercury's atmosphere consists mostly of

Venus appears to be very bright as viewed from Earth at certain times because

Which of these correctly explains why Venus has a higher surface temperature than Mercury.

What is the major difference between Mariner 10 and MESSENGER?

Viking 1 and Viking 2, the planet-exploring spacecraft, were sent to which planet?

The MOST likely source for the sulfur compounds in the clouds above the surface of Venus appears to be

Both Mercury and Earth have global magnetic fields. Compared to Earth, which feature is Mercury known to lack that is thought necessary for generating a STRONG field?

The highest temperature in the Venusian atmosphere occurs where?

Why do planetary scientists believe there are active volcanoes on Venus?

The moons of Mars are

Which of these features has NOT been seen or detected on Mars?

The reason that very few impact craters are seen on Venus compared with the Moon is believed to be that

Observers in the nineteenth century reported seeing many straight-line features crisscrossing the surface of Mars and interpreted them to be canals constructed by intelligent beings. What is the MOST likely present-day explanation for these observations?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Lives of Stars From Birth Through Middle Age

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters