Question 1

What happened during the accretion phase of the early solar system?

Accepted Answer

A) Atoms and molecules in the gas bonded together and solidified. 
B) Particles grew by colliding and sticking together. 
C) The solar nebula differentiated into metals inside of the frost line and ices beyond. 
D) Large planetesimals captured atmospheres from the solar nebula. 
E) Earth gained its oceans from icy planetesimal capture. 
A) Atoms and molecules in the gas bonded together and solidified. 
B) Particles grew by colliding and sticking together. 
C) The solar nebula differentiated into metals inside of the frost line and ices beyond. 
D) Large planetesimals captured atmospheres from the solar nebula. 
E) Earth gained its oceans from icy planetesimal capture.

Question 2

Suppose you find a rock that contains some potassium-40 (half-life of 1.3 billion years).You measure the amount and determine that there are 5 grams of potassium-40 in the rock.By measuring the amount of its decay product (argon-40)present in the rock,you realize that there must have been 40 grams of potassium-40 when the rock solidified.How old is the rock?

Accepted Answer

A) 1.3 billion years 
B) 2.6 billion years 
C) 3.9 billion years 
D) 5.2 billion years 
E) none of the above 
A) 1.3 billion years 
B) 2.6 billion years 
C) 3.9 billion years 
D) 5.2 billion years 
E) none of the above

Question 3

Nebular theory predicts that other solar systems that formed in the same way should also have 8 planets.

Accepted Answer

A) True 
 B)False

Question 4

The heavy bombardment phase of the solar system lasted

Accepted Answer

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

Question 5

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?

Accepted Answer

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

Question 6

What is the most likely reason that there are no giant planets beyond Neptune?

Accepted Answer

A) Any planets forming beyond Neptune would have drifted out of the solar system due to the weakness of the Sun's gravity at this distance. 
B) There was no material to create planetesimals beyond the orbit of Neptune. 
C) By the time planetesimals grew to a large enough mass to hold onto an atmosphere,the solar nebula had been blown away. 
D) Any planet forming beyond Neptune's orbit would have been scattered outside of the solar system by gravitational encounters. 
E) There may be,but they would be so faint that astronomers have not found them yet. 
A) Any planets forming beyond Neptune would have drifted out of the solar system due to the weakness of the Sun's gravity at this distance. 
B) There was no material to create planetesimals beyond the orbit of Neptune. 
C) By the time planetesimals grew to a large enough mass to hold onto an atmosphere,the solar nebula had been blown away. 
D) Any planet forming beyond Neptune's orbit would have been scattered outside of the solar system by gravitational encounters. 
E) There may be,but they would be so faint that astronomers have not found them yet.

Question 7

According to our theory of solar system formation,why does the Sun rotate slowly today?

Accepted Answer

A) The Sun once rotated much faster,but it transferred angular momentum to charged particles caught in its magnetic field and then blew the particles away with its strong solar wind. 
B) The Sun once rotated much faster,but it transferred angular momentum to planets and other objects during close encounters. 
C) The Sun once rotated much faster,but it lost angular momentum due to internal friction. 
D) The Sun once rotated much faster,but it lost angular momentum because everything slows down with time. 
E) The Sun was born rotating slowly because the solar nebula had very little angular momentum. 
A) The Sun once rotated much faster,but it transferred angular momentum to charged particles caught in its magnetic field and then blew the particles away with its strong solar wind. 
B) The Sun once rotated much faster,but it transferred angular momentum to planets and other objects during close encounters. 
C) The Sun once rotated much faster,but it lost angular momentum due to internal friction. 
D) The Sun once rotated much faster,but it lost angular momentum because everything slows down with time. 
E) The Sun was born rotating slowly because the solar nebula had very little angular momentum.

Question 8

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

Accepted Answer

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

Question 9

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?

Accepted Answer

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 jovian planets began from planetesimals made only of ice,while the terrestrial planets began from planetesimals made only of rock and metal. 
C) Swirling disks of gas,like the solar nebula in miniature,formed around the growing jovian planets but not around the growing terrestrial planets. 
D) The terrestrial planets formed inside the frost line of the solar nebula and the jovian planets formed beyond it. 
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 jovian planets began from planetesimals made only of ice,while the terrestrial planets began from planetesimals made only of rock and metal. 
C) Swirling disks of gas,like the solar nebula in miniature,formed around the growing jovian planets but not around the growing terrestrial planets. 
D) The terrestrial planets formed inside the frost line of the solar nebula and the jovian planets formed beyond it.

Question 10

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

Accepted Answer

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

Question 11

Suppose the planet Jupiter had never formed.How do you think the distribution of asteroids and comets in our solar system would be different? Explain.

Accepted Answer

If Jupiter had never existed,its gravity

Question 12

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?

Accepted Answer

A) 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. 
B) It was too hot for asteroids to form in this part of the solar system. 
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. 
A) 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. 
B) It was too hot for asteroids to form in this part of the solar system. 
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.

Question 13

The Moon probably formed at the same time that Earth formed,rather like the formation of a double planet.

Accepted Answer

A) True 
 B)False

Question 14

Suppose you discovered a meteorite that contains small amounts of potassium-40,which has a half-life of 1.3 billion years,and its decay product argon-40.You determine that 1/16 of the original potassium-40 remains;the other 15/16 has decayed into argon-40.How old is the meteorite? Based on your answer,where is this meteorite probably from?

Accepted Answer

To reach a fraction of 1/16,the meteorit

Question 15

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

Accepted Answer

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

Question 16

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

Accepted Answer

A) 0.5 percent 
B) 5 percent 
C) 50 percent 
D) 98 percent 
E) 100 percent 
A) 0.5 percent 
B) 5 percent 
C) 50 percent 
D) 98 percent 
E) 100 percent

Question 17

Briefly describe the modern theory of how our Moon formed.

Accepted Answer

The Moon formed from a giant i

Question 18

Some radioactive isotopes found in meteorites suggest that the solar system may have been formed shortly after a supernova occurred nearby.

Accepted Answer

A) True 
 B)False

Question 19

In essence,the nebular theory holds that

Accepted Answer

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

Question 20

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

Accepted Answer

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

Exam 8: Formation of the Solar System

What happened during the accretion phase of the early solar system?

Nebular theory predicts that other solar systems that formed in the same way should also have 8 planets.

The heavy bombardment phase of the solar system lasted

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?

What is the most likely reason that there are no giant planets beyond Neptune?

According to our theory of solar system formation,why does the Sun rotate slowly today?

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

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?

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

Suppose the planet Jupiter had never formed.How do you think the distribution of asteroids and comets in our solar system would be different? Explain.

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?

The Moon probably formed at the same time that Earth formed,rather like the formation of a double planet.

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

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

Briefly describe the modern theory of how our Moon formed.

Some radioactive isotopes found in meteorites suggest that the solar system may have been formed shortly after a supernova occurred nearby.

In essence,the nebular theory holds that

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

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light and Matter: Reading Messages from the Cosmos

Telescopes: Portals of Discovery

Our Planetary System

Planetary Geology: Earth and the Other Terrestrial Worlds

Planetary Atmospheres: Earth and the Other Terrestrial Worlds

Jovian Planet Systems

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: The New Science of Distant Worlds

Our Star

Surveying the Stars

Star Birth

Star Stuff

The Bizarre Stellar Graveyard

Our Galaxy

Galaxies and the Foundations of Modern Cosmology

Galaxy Evolution

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

Celestial Timekeeping and Navigation

Space and Time

Spacetime and Gravity

Building Blocks of the Universe

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