Chapter 7-8 Homework

What are the main constituents of the jovian planets? A) nitrogen and methane B) hydrogen and helium C) ammonia and methane D) rocky minerals and water, as on Earth E) ammonia and water

B) hydrogen and helium

The more massive planets in the solar system tend to be less dense than the lower mass planets. True False

True

Which planet, other than Earth, has visible water ice on it? A) Mars B) Jupiter C) the Moon D) Venus E) Mercury

A) Mars

According to the nebular theory, what are asteroids and comets? A) They are leftover planetesimals that never accreted into planets. B) They are the shattered remains of collisions between planets. C) They are the shattered remains of collisions between moons. D) They are chunks of rock or ice that were expelled from planets by volcanoes. E) They are chunks of rock or ice that condensed long after the planets and moons had formed.

A) They are leftover planetesimals that never accreted into planets.

The planet closest in size to Earth is A) Venus. B) the Moon. C) Mars. D) Pluto. E) Mercury.

A) Venus.

Which of the following is furthest from the Sun? A) a comet in the Oort cloud B) Pluto C) a comet in the Kuiper belt D) an asteroid in the asteroid belt E) Neptune

A) a comet in the Oort cloud

Where does nuclear fusion occur in the Sun? A) in its core B) on the surface C) just above the visible surface D) anywhere below the surface E) all of the above

A) in its core

Astronomers have decided that, rather than being a planet, Pluto is really just a large member of A) the Kuiper belt. B) the asteroid belt. C) the Oort cloud. D) an extrasolar planetary system. E) the moon system around Neptune.

A) the Kuiper belt.

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

False

All planets orbit the Sun in the same direction (counterclockwise as viewed from above Earth's North Pole). True False

True

Oceans cover more of Earth's surface than land. True False

True

According to the nebular theory, how did the Oort cloud form? A) It is made of planetesimals formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets. B) It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form a planet. C) It is made of planetesimals between the orbits of Mars and Jupiter that never formed into a planet. D) It is material left over from the interstellar cloud that never contracted with the rest of the gases to form the solar nebula. E) It consists of objects that fragmented from the protosun during a catastrophic collision early in the formation of the solar system.

A) It is made of planetesimals formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets.

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

B) As the cloud shrank, its gravitational potential energy was converted to kinetic energy and then into thermal energy.

How do asteroids differ from comets? A) Asteroids are made of icy material and are less dense than the comets, which are rockier. B) Asteroids are rocky bodies and are denser than the comets, which are made of icy material. C) Asteroids are rocky bodies and are less dense than the comets, which are made of icy material. D) Asteroids are made of icy material and are denser than the comets, which are more rocky. E) Asteroids and comets are both made of rocky and icy material, but asteroids are smaller in size than comets.

B) Asteroids are rocky bodies and are denser than the comets, which are made of icy material.

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

B) Particles grew by colliding and sticking together.

Based on our current theory of Earth's formation, the water we drink comes from A) chemical reactions that occurred in Earth's core after Earth formed. B) comets that impacted Earth. 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) chemical reactions that occurred in Earth's crust after Earth formed.

B) comets that impacted Earth.

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

B) metals

The heavy bombardment phase of the solar system lasted A) several tens of millions of years. B) several hundreds of millions of years. C) several million years. D) about a billion years. E) to the present time.

B) several hundreds of millions of years.

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

B) the equal number of terrestrial and jovian planets

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

B) the oldest meteorites.

Observations of young stars (as well as theory) tell us that when the Sun was young the solar wind A) was weaker than it is today. B) was stronger than it is today. C) blew outward only along the Sun's poles. D) was nonexistent. E) was about the same strength as it is today.

B) was stronger than it is today.

What is the primary reason why a Pluto flyby mission would be cheaper than a Pluto orbiter? A) The flyby is easier to design than the orbiter. B) The fuel needed for an orbiter to slow down when it reaches Pluto is very expensive in and of itself. C) The fuel needed for an orbiter to slow down when it reaches Pluto adds a lot of weight to the spacecraft. D) The flyby can use less expensive cameras than the orbiter. E) The question is incorrect; in general, orbiters are cheaper than flybys.

C) The fuel needed for an orbiter to slow down when it reaches Pluto adds a lot of weight to the spacecraft.

Which is the densest planet in the solar system? A) Venus B) Mercury C) Earth D) Mars E) Jupiter

C) Earth

Why are the inner planets made of denser materials than the outer planets? A) The Sun's gravity pulled denser materials toward the inner part of the solar nebula, while lighter gases escaped more easily. B) When the solar nebula formed a disk, materials naturally segregated into bands, and in our particular solar system the denser materials settled nearer the Sun while lighter materials are found in the outer part. C) In the inner part of the nebula only metals and rocks were able to condense because of the high temperatures, whereas hydrogen compounds, although more abundant, were only able to condense in the cooler outer regions. D) Denser materials were heavier and sank to the center of the nebula. E) In the beginning, when the protoplanetary disk was spinning faster, centrifugal forces flung the lighter materials toward the outer parts of the solar nebula.

C) In the inner part of the nebula only metals and rocks were able to condense because of the high temperatures, whereas hydrogen compounds, although more abundant, were only able to condense in the cooler outer regions.

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

C) It flattened as a natural consequence of collisions between particles in the nebula, changing random motions into more orderly ones.

According to our theory of solar system formation, why do we find some exceptions to the general rules and patterns of the planets? A) Our theory is not quite correct because it cannot explain these exceptions. B) The exceptions probably represent objects that were captured by our solar system from interstellar space. C) Most of the exceptions are the result of giant impacts. D) The exceptions exist because, even though our theory is as correct as possible, nature never follows rules precisely. E) The exceptions probably represent objects that formed recently, rather than early in the history of the solar system.

C) Most of the exceptions are the result of giant impacts.

Which of the following statements is not an observed pattern of motion in our solar system? A) Most planetary orbits lie nearly in the same plane. B) All planets orbit the Sun in the same direction. C) Most planets orbit at the same speed. D) Most planets rotate in the same direction in which they orbit. E) Almost all moons orbit their planet in the same direction as the planet's rotation.

C) Most planets orbit at the same speed.

Where are most of the known asteroids found? A) in the Oort cloud B) in the Kuiper belt C) between the orbits of Mars and Jupiter D) between the orbits of the terrestrial planets E) between the orbits of the jovian planets

C) between the orbits of Mars and Jupiter

Which of the following best describes Pluto in terms of the general characteristics of terrestrial and jovian planets? A) solid surface and temperature similar to terrestrial planets; distance and density similar to jovian planets B) size and distance similar to terrestrial planets; gaseous surface and composition similar to jovian planets C) size and solid surface similar to terrestrial planets; distance similar to jovian planets D) solid surface and density similar to terrestrial planets; temperature and composition similar to jovian planets E) size and density similar to terrestrial planets; distance and composition similar to jovian planets

C) size and solid surface similar to terrestrial planets; distance similar to jovian planets

Which of the following has not been detected around other stars in the Galaxy? A) flattened, spinning disks B) a collapsing nebula of gas C) terrestrial planets D) strong stellar winds E) jovian planets

C) terrestrial planets

Based on the frequency with which we see comets from Earth, astronomers estimate the total number of comets in the solar system to be A) 1 billion. B) 100 billion. C) 10 billion. D) 1 trillion. E) 100 million.

D) 1 trillion.

What percentage of the solar nebula's mass consisted of hydrogen and helium gases? A) 5 percent B) 50 percent C) 0.5 percent D) 98 percent E) 100 percent

D) 98 percent

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.

D) It is a thousand times more massive than all the planets combined.

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

D) They were produced inside stars.

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) Any planets that once orbited in the opposite direction or a different plane were ejected from the solar system. B) The original solar nebula happened to be disk-shaped by chance. 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) Luck explains it, as we would expect that most other solar systems would not have all their planets orbiting in such a pattern. E) The laws of conservation of energy and conservation of angular momentum ensure that any rotating, collapsing cloud will end up as a spinning disk.

E) The laws of conservation of energy and conservation of angular momentum ensure that any rotating, collapsing cloud will end up as a spinning disk

Which of the following is not a characteristic of the inner planets? A) They all have solid, rocky surfaces. B) Their orbits are relatively closely spaced. C) They have very few, if any, satellites. D) They are relatively smaller than the outer planets. E) They all have substantial atmospheres.

E) They all have substantial atmospheres.

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

E) They reveal that the age of the solar system is approximately 4.6 billion years.

Which of the following is the origin of almost all the large moons around the jovian planets? A) They were formed by giant impacts. B) They are captured asteroids. C) They are captured comets. D) They are captured planets. E) They were formed by condensation and accretion in a disk of gas around the planet.

E) They were formed by condensation and accretion in a disk of gas around the planet.

Which of the following are relatively unchanged fragments from the early period of planet building in the solar system? A) Oort cloud comets B) asteroids C) Kuiper belt comets D) the moons of Mars E) all of the above

E) all of the above

What was the frost line of the solar system? A) the distance from the Sun where temperatures were low enough for hydrogen and helium to condense, between the present-day orbits of Jupiter and Saturn B) the distance from the Sun where temperatures were low enough for asteroids to form, between the present-day orbits of Venus and Earth C) the distance from the Sun where temperatures were low enough for metals to condense, between the Sun and the present-day orbit of Mercury D) the distance from the Sun where temperatures were low enough for rocks to condense, between the present-day orbits of Mercury and Venus E) the distance from the Sun where temperatures were low enough for hydrogen compounds to condense into ices, between the present-day orbits of Mars and Jupiter

E) the distance from the Sun where temperatures were low enough for hydrogen compounds to condense into ices, between the present-day orbits of Mars and Jupiter

All the planets in the solar system have at least one moon. True False

False

All the planets in the solar system rotate in the same direction as they orbit the Sun. True False

False

All four of the giant outer planets â Jupiter, Saturn, Uranus, and Neptune â have rings. True False

True