Deck 6: Formation of the Solar System

Question 1

The region of our solar system between Mercury and Mars has very few asteroids, while the region between Mars and Jupiter has many asteroids. Based on what you have learned, what is the most likely explanation for the lack of asteroids between Mercury and Mars?

A)It was too hot for asteroids to form in this part of the solar system.
B)There were very few planetary leftovers in this region because most of the solid material was accreted by the terrestrial planets as the planets formed.
C)Gravity was too weak to allow asteroids to form in this part of the solar system.
D)All the asteroids that formed between Mercury and Mars later migrated to the asteroid belt between Mars and Jupiter.

Answer 1

B

Question 2

Which of the following is furthest from the Sun?

A)a comet in the Kuiper belt
B)Pluto
C)a comet in the Oort cloud
D)an asteroid in the asteroid belt
E)Neptune

Answer 2

C

Question 3

Which of the following statements about our Sun is not true?

A)The Sun is made mostly of hydrogen and helium.
B)The Sun is a star.
C)The Sun contains more than 99% of all the mass in our solar system.
D)The Sun's diameter is about 5 times that of Earth.

Answer 3

D

Question 4

Astronomers now classify Pluto as really just a large member of

A)the moon system around Neptune.
B)the Oort cloud.
C)an extrasolar planetary system.
D)the Kuiper belt.
E)the asteroid belt.

Question 5

According to our theory of solar system formation, which law best explains why the solar nebula spun faster as it shrank in size?

A)the law of universal gravitation
B)the law of conservation of energy
C)the law of conservation of angular momentum
D)Einstein's law E = mc2

Question 6

What are the main constituents of the jovian planets?

A)hydrogen and helium
B)ammonia and water
C)nitrogen and methane
D)rocky minerals and water, as on Earth
E)ammonia and methane

Question 7

If a radioactive isotope that was injected into your bloodstream has a half- life of 5 hours, how many hours do you have to wait before the amount of this isotope in your body is 1 its original 16
Amount?

A)25
B)15
C)20
D)5
E)10

Question 8

According to our theory of solar system formation, what are asteroids and comets?

A)chunks of rock or ice that were expelled from planets by volcanoes
B)the shattered remains of collisions between planets
C)chunks of rock or ice that condensed after the planets and moons finished forming
D)leftover planetesimals that never accreted into planets

Question 9

The age of the solar system can be established by radioactive dating of

A)the atmosphere of Mars.
B)the oldest meteorites.
C)the oldest rocks on the Moon.
D)the oldest rocks on Earth.
E)It hasn't been done yet, but the age of the solar system could be obtained from a sample of Io's surface.

Question 10

How do we know the mass of Neptune?

A)the size and density of Neptune
B)the periods and sizes of the orbits of the moons around Neptune
C)the distance of Neptune from the Earth and its rotation period
D)the period and size of Neptune's orbit around the Sun
E)the orbital speed of Neptune moving around the Sun

Question 11

Which of the following lists the ingredients of the solar nebula from highest to lowest percentage of mass of the nebula?

A)hydrogen compounds (H2O, CH4, NH3), rocks, metals, light gases (H, He)
B)hydrogen compounds (H2O, CH4, NH3), light gases (H, He), rocks, metals
C)light gases (H, He), hydrogen compounds (H2O, CH4, NH3), rocks, metals
D)light gases (H, He), hydrogen compounds (H2O, CH4, NH3), metals, rocks
E)hydrogen compounds (H2O, CH4, NH3), light gases (H, He), metals, rocks

Question 12

According to our present theory of solar system formation, how did Earth end up with enough water to make oceans?

A)The water was brought to the forming Earth by planetesimals that accreted beyond the orbit of Mars.
B)Earth formed at a distance from the Sun at which liquid water happened to be plentiful in the solar nebula.
C)The water was formed by chemical reactions among the minerals in the Earth's core.
D)The water was brought to the forming Earth by planetesimals that accreted near Earth's orbit.

Question 13

In what way is Venus most similar to Earth?

A)Both planets have similar surface geology.
B)Both planets have very similar atmospheres.
C)Both planets have warm days and cool nights.
D)Both planets are nearly the same size.

Question 14

What do we mean by accretion in the context of planet formation?

A)the solidification of ices, rocks, and metal from the gas of the solar nebular
B)the growth of planetesimals from smaller solid particles that collided and stuck together
C)the growth of the Sun as the density of gas increased in the center of the solar nebula
D)the formation of moons around planets

Question 15

Imagine a planet like Earth orbiting the Sun, at an average distance of 1 AU but with a highly eccentric orbit. Which of the following statements about this orbit is not true?

A)The planet does not maintain a constant speed around the Sun.
B)The period is longer than a year.
C)The planet is sometimes very close to the Sun, and sometimes very far.
D)The seasons are very extreme.

Question 16

Which of the following discoveries would cause us to re- evaluate the nebular theory for forming planets?

A)A star's 5 terrestrial planets orbit in the opposite direction of its 3 jovian planets.
B)Of the star's five terrestrial planets, one has a large moon.
C)Two of the star's planets are rotating in directions backwards compared to their orbital direction.
D)A star has zero planets.
E)A star has 20 planets.

Question 17

Observations vs. Explanations. Which of the following statements is an explanation?

A)The orderly orbits of planets arose from their formation in a rotating cloud of gas.
B)The farther a galaxy is, the faster it is moving away from us.
C)All planets orbit the Sun in the same direction and nearly the same plane.
D)The inner planets of the solar system are rocky and the outer planets are gas giants.
E)Hydrogen and helium are important constituents of stars.

Question 18

Suppose you view the solar system from high above Earth's North Pole. Which of the following statements about planetary orbits will be true?

A)All the planets except Uranus orbit the Sun counterclockwise; Uranus orbits in the opposite direction.
B)All the planets orbit counterclockwise around the Sun.
C)The inner planets orbit the Sun clockwise while the outer planets orbit the Sun counterclockwise.
D)The inner planets orbit the Sun counterclockwise while the outer planets orbit the Sun clockwise.

Question 19

What do we mean by the period of heavy bombardment in the context of the history of our solar system?

A)the time before planetesimals finished accreting into planets, during which many growing planetesimals must have shattered in collisions
B)the time during which heavy elements condensed into rock and metal in the solar nebula
C)the period about 65 million years ago when an impact is thought to have led to the extinction of the dinosaurs
D)the first few hundred million years after the planets formed, which is when most impact craters were formed

Question 20

According to our present theory of solar system formation, why were solid planetesimals able to grow larger in the outer solar system than in the inner solar system?

A)because gas in the outer solar system contained a larger proportion of rock, metal, and hydrogen compounds than the gas in the inner solar system
B)because only metal and rock could condense in the inner solar system, while ice also condensed in the outer solar system
C)because only the outer planets captured hydrogen and helium gas from the solar nebula
D)because the Sun's gravity was stronger in the outer solar system, allowing more solid material to collect

Question 21

Why did the solar nebula heat up as it collapsed?

A)Radiation from other nearby stars that had formed earlier heated the nebula.
B)The shock wave from a nearby supernova heated the gas.
C)Collisions among planetesimals generated friction and heat.
D)Nuclear fusion occurring in the core of the protosun produced energy that heated the nebula.
E)As the cloud shrank, its gravitational potential energy was converted to thermal energy.

Question 22

Why did the solar nebula flatten into a disk?

A)The interstellar cloud from which the solar nebula formed was originally somewhat flat.
B)It flattened as a natural consequence of collisions between particles in the nebula, changing random motions into more orderly ones.
C)The force of gravity pulled the material downward into a flat disk.
D)As the nebula cooled, the gas and dust settled onto a disk.

Question 23

According to our theory of solar system formation, why do all the planets orbit the Sun in the same direction and in nearly the same plane?

A)The original solar nebula happened to be disk- shaped by chance.
B)The laws of conservation of energy and conservation of angular momentum ensure that any rotating, collapsing cloud will end up as a spinning disk.
C)The Sun formed first, and as it grew in size it spread into a disk, rather like the way a ball of dough can be flattened into a pizza by spinning it.
D)Any planets that once orbited in the opposite direction or a different plane were ejected from the solar system.
E)Luck explains it, as we would expect that most other solar systems would not have all their planets orbiting in such a pattern.

Question 24

Pluto is different from the other outer planets in all of the following ways except which one?

A)It has only one moon.
B)Its orbit is not very close to being circular.
C)It doesn't have rings.
D)Its surface temperature is very cold.
E)It is made mostly of ices.

Question 25

The planet closest in size to Earth is

A)the Moon.
B)Mars.
C)Mercury.
D)Venus.
E)Pluto.

Question 26

The following statements are all true. Which one counts as an "exception to the rule" in being unusual for our solar system?

A)Venus does not have a moon.
B)Jupiter has a very small axis tilt.
C)Saturn has no solid surface.
D)The diameter of Earth's Moon is about 1/4 that of Earth.

Question 27

The terrestrial planets in our solar system are .

A)Mars, Jupiter, Saturn, Uranus, and Neptune
B)Pluto and Eris
C)Mercury, Venus, Earth, and Mars
D)Jupiter, Saturn, Uranus, and Neptune

Question 28

Which of the following is the origin of almost all the large moons around the jovian planets?

A)They were formed by condensation and accretion in a disk of gas around the planet.
B)They are captured asteroids.
C)They are captured comets.
D)They were formed by giant impacts.
E)They are captured planets.

Question 29

How do scientists estimate how old the solar system is?

A)They make a guess: no one really knows how old the solar system is.
B)They measure the speeds and distances of galaxies, and calculate the time it took for them to travel that distance.
C)They measure the abundances of radioactive elements in meteorites, and use their half- lives to calculate the age.
D)They look up the answer in a book.
E)They measure how fast the Sun is losing energy, and how much energy it has to lose.

Question 30

Which planet, other than Earth, has visible water ice on it?

A)Jupiter
B)the Moon
C)Mars
D)Mercury
E)Venus

Question 31

Suppose you find a rock that contains 10 micrograms of radioactive potassium- 40, which has a half- life of 1.25 billion years. By measuring the amount of its decay product (argon- 40)present in the rock, you conclude that there must have been 80 micrograms of potassium- 40 when the rock solidified. How old is the rock?

A)1)25 billion years
B)5)0 billion years
C)2)5 billion years
D)3)75 billion years

Question 32

Mars has two moons that are most similar in character to .

A)Earth's Moon
B)particles in the rings of Saturn
C)comets
D)small asteroids

Question 33

Based on our current theory of Earth's formation, the water we drink comes from

A)chemical reactions that occurred in Earth's crust after Earth formed.
B)chemical reactions that occurred in Earth's core after Earth formed.
C)material left behind during the giant impact that formed the Moon.
D)ice that condensed in the solar nebula in the region where Earth formed.
E)comets that impacted Earth.

Question 34

Which of the following observations indicates that conditions on Mars may have been suitable for life in the past?

A)There are very large extinct volcanoes on Mars.
B)Mars has two small moons.
C)There are dried- up riverbeds on Mars.
D)Mars has polar caps made of "dry ice."
E)There is a very deep and long canyon that extends across Mars.

Question 35

The nebular theory of the formation of the solar system successfully predicts all but one of the following. Which one does the theory not predict?

A)Planets orbit around the Sun in nearly circular orbits in a flattened disk.
B)the presence of asteroids and comets
C)the equal number of terrestrial and jovian planets
D)the compositional differences between the terrestrial and jovian planets
E)the craters on the Moon

Question 36

A rock sample from the moon includes a mineral that contains small amounts of the radioactive isotope Potassium- 40 and its daughter element Argon- 40 (half- life of 1.3 billion years). This mineral would not form with any Argon- 40. Consider a crystal with 7 atoms of Argon- 40 for every 1 atom of Potassium- 40. How long ago did this crystal form?

A)13.5 billion years ago
B)1)3 billion years ago
C)3)9 billion years ago
D)5)2 billion years ago

Question 37

Many meteorites appear to have formed very early in the solar system's history. How do these meteorites support our theory about how the terrestrial planets formed?

A)The meteorites' sizes are just what we'd expect if metal and rock condensed and accreted as our theory suggests.
B)The meteorites' appearance and composition is just what we'd expect if metal and rock condensed and accreted as our theory suggests.
C)Their overall composition is just what we believe the composition of the solar nebula to have been: mostly hydrogen and helium.
D)Their appearance and composition matches what we observe in comets today, suggesting that they were once pieces of icy planetesimals.

Question 38

Suppose you start with 1 kilogram of a radioactive substance that has a half- life of 10 years. Which of the following statements will be true after 20 years pass?

A)You'll have 0.75 kilogram of the radioactive substance remaining.
B)You'll have 0.25 kilogram of the radioactive substance remaining.
C)All the material will have completely decayed.
D)You'll have 0.5 kilogram of the radioactive substance remaining.

Question 39

Where did the elements heavier than hydrogen and helium come from?

A)They evolved from hydrogen and helium shortly after the Big Bang.
B)They were produced inside dense interstellar gas.
C)They were produced in the Big Bang.
D)They were produced inside stars.
E)All of the above

Question 40

What do meteorites reveal about the solar system?

A)They reveal that the age of the solar system is approximately 4.6 billion years.
B)Nothing, because they come from other star systems.
C)They reveal that the early solar system consisted mostly of hydrogen and helium gas.
D)They reveal that meteorites are much older than the comets and planets.
E)They reveal that the solar system once contained 10 planets.

Question 41

Which of the following types of material can condense into what we call ice at low temperatures?

A)hydrogen and helium
B)metal
C)rock
D)hydrogen compounds

Question 42

Where does nuclear fusion occur in the Sun?

A)on the surface
B)just above the visible surface
C)anywhere below the surface
D)in its core
E)all of the above

Question 43

Which of the following lists the planets of our solar system in the correct order from closest to farthest from the Sun?

A)Mercury, Venus, Mars, Earth, Saturn, Jupiter, Neptune, Uranus
B)Mercury, Earth, Venus, Mars, Jupiter, Saturn, Neptune, Uranus
C)Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
D)Earth, Mars, Mercury, Venus, Jupiter, Saturn, Uranus, Neptune

Question 44

According to modern scientific dating techniques, approximately how old is the solar system?

A)14 billion years
B)10,000 years
C)4)5 billion years
D)4)6 million years

Question 45

Suppose that the temperature of the solar nebula had been much colder. How might the Solar System look different today?

A)Terrestrial planets may have formed at a larger distance from the Sun.
B)The gas giant planets might be bigger and farther from the Sun.
C)More planets would have formed.
D)The gas giant planets might be bigger and closer to the Sun.

Question 46

How do scientists determine the age of the solar system?

A)radiometric dating of Moon rocks
B)radiometric dating of meteorites
C)radiometric dating of the oldest Earth rocks
D)Theoretical calculations tell us how long it has taken the planets to evolve to their present forms.

Question 47

What do we mean by the frost line when we discuss the formation of planets in the solar nebula?

A)It marks the special distance from the Sun at which hydrogen compounds become abundant; closer to the Sun, there are no hydrogen compounds.
B)It is a circle at a particular distance from the Sun, beyond which the temperature was low enough for ices to condense.
C)It is another way of stating the temperature at which water freezes into ice.
D)It is the altitude in a planet's atmosphere at which snow can form.

Question 48

Compared to the distance between Earth and Mars, the distance between Jupiter and Saturn is .

A)just slightly less
B)about the same
C)much smaller
D)much larger

Question 49

According to our theory of solar system formation, what three major changes occurred in the solar nebula as it shrank in size?

A)It gained energy, it gained angular momentum, and it flattened into a disk.
B)It got hotter, its rate of rotation increased, and it flattened into a disk.
C)Its mass, temperature, and density all increased.
D)Its gas clumped up to form the terrestrial planets, nuclear fusion produced heavy elements to make the jovian planets, and central temperatures rose to more than a trillion Kelvin.

Question 50

The heavy bombardment phase of the solar system lasted

A)about a billion years.
B)to the present time.
C)several tens of millions of years.
D)several million years.
E)several hundreds of millions of years.

Question 51

Which planet could an astronaut visit without the need for a spacesuit (and survive)?

A)the Moon
B)Mars
C)Mercury
D)Venus
E)None; an astronaut would need a spacesuit to survive a visit to any other planet in the solar system.

Question 52

Which of the following statements does not apply to the formation of gas giants like Jupiter, compared to terrestrial planets?

A)surface dramatically altered during bombardment
B)caused icy planetesimals to slingshot away from the Sun, to become Oort cloud comets
C)formed in regions cold enough for water to freeze
D)accreted from icy planetesimals
E)formed in a region with lower orbital speeds

Question 53

Which of the following statements about the accelerations and gravitational forces between a planet and a star is true?

A)Forces are equal and opposite; the planet is accelerated more than the star.
B)Forces are equal and opposite; the star is accelerated more than the planet.
C)Acceleration is equal and opposite; the planet feels more force more than the star.
D)Acceleration is equal and opposite; the star feels more force more than the planet.
E)Accelerations and forces are both equal and opposite.

Question 54

What kind of material in the solar nebula could remain solid at temperatures as high as 1,500 K, such as existed in the inner regions of the nebula?

A)metals
B)molecules such as methane and ammonia
C)rocks
D)hydrogen compounds
E)silicon- based minerals

Question 55

Imagine that an alien spaceship crashed onto Earth. Which statement would most likely be true?

A)The aliens' home world is another planet in our own solar system.
B)All the evidence of the crash would be quickly whisked off by the U.S. military to Area 51 in Nevada.
C)The crash would create a noticeable crater.
D)It would crash in the ocean.

Question 56

Which of the following is not evidence supporting the idea that our Moon formed as a result of a giant impact?

A)The Moon has a much smaller proportion of easily vaporized materials than Earth.
B)Computer simulations show that the Moon could really have formed in this way.
C)The Moon's average density suggests it is made of rock much more like that of the Earth's outer layers than that of the Earth as a whole.
D)The Pacific Ocean appears to be a large crater-probably the one made by the giant impact.

Question 57

Which of the following is not a major pattern of motion in the solar system?

A)Most of the solar system's large moons orbit in their planet's equatorial plane.
B)The Sun and most of the planets rotate in the same direction in which the planets orbit the Sun.
C)All of the planets orbit the Sun in the same direction-counterclockwise as viewed from above Earth's north pole.
D)Nearly all comets orbit the Sun in same direction and roughly the same plane.

Question 58

Which of the following puzzles in the solar system cannot be explained by a giant impact event?

A)the backward rotation of Venus
B)the large metallic core of Mercury
C)the orbit of Triton in the opposite direction to Neptune's rotation
D)the formation of the Moon
E)the extreme axis tilt of Uranus

Question 59

What percentage of the solar nebula's mass consisted of hydrogen and helium gases?

A)98 percent
B)5 percent
C)0)5 percent
D)100 percent
E)50 percent

Question 60

If the freezing point of ices of all types were at a much lower temperature, what change would that imply for the formation of our solar system?

A)There would be no change in where gas giants could form, because the freezing point of ices did not affect the formation of gas giants.
B)The gas giants would have to form at a larger distance.
C)The gas giants could have formed at a closer distance.

Question 61

Which of the following is not an exception to the general patterns of motion in the solar system?

A)the extreme axis tilt of Uranus
B)the large size of Earth's moon
C)the counterclockwise rotation of Venus
D)the rings of Saturn
E)the "backward" orbit of Triton around Neptune

Question 62

If the proto star that became our Sun had been hotter and more luminous when it formed, what changes (if any)might have been experienced by our Solar System?

A)Jupiter would now be farther from the Sun.
B)The Moon would not exist.
C)Terrestrial planes could only have formed closer to the Sun.
D)Mars would be a gas giant.
E)No comets could have formed.

Question 63

According to present understanding, which of the following statements about the solar wind is not true?

A)It swept vast amounts of gas from the solar nebula into interstellar space.
B)It consists of charged particles blown off the surface of the Sun.
C)It is even stronger today than it was when the Sun was young.
D)It helped in the transfer of angular momentum from the young Sun to particles that blew into interstellar space, which explains why the Sun rotates so slowly today.

Question 64

In what way is Pluto more like a comet than a planet?

A)It is made mostly of rock and ice.
B)It has a long tail. It has a moon.
C)It sometimes enters the inner solar system.

Question 65

Which planet has the highest average surface temperature, and why?

A)Mercury, because of its dense carbon dioxide atmosphere
B)Jupiter, because it is so big
C)Mars, because of its red color
D)Mercury, because it is closest to the Sun
E)Venus, because of its dense carbon dioxide atmosphere

Question 66

In essence, the nebular theory holds that .

A)the planets each formed from the collapse of its own separate nebula
B)The nebular theory is a discarded idea that imagined planets forming as a result of a near- collision between our Sun and another star.
C)our solar system formed from the collapse of an interstellar cloud of gas and dust
D)nebulae are clouds of gas and dust in space

Question 67

Where are most of the known asteroids found?

A)between the orbits of Mars and Jupiter
B)between the orbits of the terrestrial planets
C)in the Kuiper belt
D)between the orbits of the jovian planets
E)in the Oort cloud

Question 68

According to our present theory of solar system formation, which of the following lists the major ingredients of the solar nebula in order from the most abundant to the least abundant?

A)hydrogen compounds; hydrogen and helium gas; metal; rock
B)hydrogen and helium gas; hydrogen compounds; rock; metal
C)hydrogen and helium gas; rock; metal; hydrogen compounds
D)hydrogen, water, methane, helium

Question 69

Which planet (besides Earth)has been visited by the largest number of robotic spacecraft?

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

Question 70

According to our theory of solar system formation, which law best explains why the central regions of the solar nebula got hotter as the nebula shrank in size?

A)the law of conservation of angular momentum
B)the law of conservation of energy
C)Newton's third law
D)the two laws of thermal radiation

Question 71

Which of the following statements best explains why the planets orbit in nearly a single plane and in the same direction around the Sun?

A)The planets all rotate in same direction as they orbit.
B)The planets formed from a disk of rotating gas.
C)The Sun rotates in the same direction, and spun out the planets as it formed.
D)It's a mysterious coincidence: the planets form randomly, so it's a puzzle how they orbit that way.

Question 72

How does the Sun's mass compare with that of the planets?

A)It is a hundred times more massive than all the planets combined.
B)It is a hundred times more massive than Earth.
C)It is a thousand times more massive than Earth.
D)It is a thousand times more massive than all the planets combined.
E)It is about as massive as all the planets combined.

Question 73

What is the primary basis upon which we divide the ingredients of the solar nebula into four categories (hydrogen/helium; hydrogen compound; rock; metal)?

A)the amounts of energy required to ionize various materials
B)the temperatures at which various materials will condense from gaseous form to solid form
C)the atomic mass numbers of various materials
D)the locations of various materials in the solar nebula

Question 74

When we say that jovian planets contain significant amounts of hydrogen compounds, we mean all the following chemicals except .

A)carbon dioxide
B)methane
C)ammonia
D)water

Question 75

Which jovian planet does not have rings?

A)All the jovian planets have rings.
B)Uranus
C)Mars
D)Neptune
E)Jupiter

Question 76

Which of the following is not a characteristic of the inner planets?

A)They are relatively smaller than the outer planets.
B)They have very few, if any, satellites.
C)They all have solid, rocky surfaces.
D)They all have substantial atmospheres.
E)Their orbits are relatively closely spaced.

Question 77

What percentage of the solar nebula's mass consisted of rocky material?

A)0)4 percent
B)0 percent
C)80 percent
D)20 percent
E)2 percent

Question 78

Which of the following statements about Mars is not true?

A)We have landed spacecraft on its surface.
B)It is frozen today, but once had flowing water.
C)We could survive on Mars without spacesuits, as long as we brought oxygen in scuba tanks.
D)It is considered part of our inner solar system.

Question 79

According to our present theory of solar system formation, which of the following statements about the growth of terrestrial and jovian planets is not true?

A)Both types of planet begun with planetesimals growing through the process of accretion, but only the jovian planets were able to capture hydrogen and helium gas from the solar nebula.
B)The terrestrial planets formed inside the frost line of the solar nebula and the jovian planets formed beyond it.
C)The jovian planets began from planetesimals made only of ice, while the terrestrial planets began from planetesimals made only of rock and metal.
D)Swirling disks of gas, like the solar nebula in miniature, formed around the growing jovian planets but not around the growing terrestrial planets.

Question 80

What percentage of the mass of the solar nebula consisted of elements other than hydrogen and helium?

A)0)1 percent
B)80 percent
C)2 percent
D)20 percent
E)0 percent