Last saved by: Asma Said

CHAPTER 8—ORIGIN OF THE SOLAR SYSTEM AND EXTRASOLAR PLANETS

MULTIPLE CHOICE

	1.	The iron in our solar system was created from smaller mass atomic nuclei in  ______.
a. | the Earth
b. | our sun
c. | Jupiter
d. | the Big Bang
e. | supernovas

ANS:	E	PTS:	1

	2.	The hydrogen in our solar system was created from subatomic particles in  ______.
a. | the Earth
b. | our sun
c. | Jupiter
d. | the Big Bang
e. | supernovas

ANS:	D	PTS:	1

	3.	The oldest rocks found on Earth are about ____ years old.
a. | 14 billion
b. | 10.5 billion
c. | 7.0 billion
d. | 3.9 billion

ANS:	D	PTS:	1

	4.	An extrasolar planet is
a. | a planet that orbits our sun that we have not yet discovered.
b. | one not needed for the formation of our solar system which is kept in a special area just in case.
c. | a planet found orbiting around a star other than the sun.
d. | another name for an asteroid.
e. | a planet extra close to our sun.

ANS:	C	PTS:	1

	5.	____ are located beyond the asteroid belt (3 AU)  from the sun, have extremely large masses and very low densities.
a. | Comets
b. | Extrasolar planets
c. | Asteroids
d. | Terrestrial planets
e. | Jovian planets

ANS:	E	PTS:	1

	6.	The satellites discovered by Galileo
a. | orbit the planet Jupiter.
b. | orbit the terrestrial planets.
c. | orbit asteroids.
d. | orbit Mars.
e. | orbit extrasolar planets.

ANS:	A	PTS:	1

	7.	The first small solid grains or flakes formed in our solar system by the process of ____, the addition of material to an object an atom or molecule at a time.
a. | Accretion
b. | Sublimation
c. | Hydration
d. | Condensation
e. | Vaporization

ANS:	D	PTS:	1

	8.	The first solid grains of ______ formed in hot regions near the sun. Much farther from the sun the first grains (or rather flakes) of ________also formed by a similar process as the close-in grains, _______.
a. | water ice; iron; accretion
b. | iron: water ice; accretion
c. | water ice; iron; condensation
d. | iron; water ice; condensation

ANS:	D	PTS:	1

	9.	After the first solid grains formed in our solar system, these particles could then grow by the process of ____, the collision and sticking of one particle with another to continue the formation of planetesimals.  Each of these has many atoms or molecules.
a. | Accretion
b. | Sublimation
c. | Hydration
d. | Condensation
e. | Vaporization

ANS:	A	PTS:	1

	10.	Protoplanets
a. | grew in size primarily by accretion.
b. | grew in size primarily by condensation.
c. | are still visible today as the terrestrial planets.
d. | grew in size by collecting the particles in the solar wind.
e. | grew in size by the collision and coalescing of planetesimals.

ANS:	E	PTS:	1

	11.	____ is the separation of material in a newly formed planet or asteroid according to density.  This happens when the object becomes molten.
a. | Accretion
b. | Differentiation
c. | Condensation
d. | Outgassing
e. | Sublimation

ANS:	B	PTS:	1

	12.	A newly formed planet or large asteroid becomes molten due to ______.
a. | the last infalling objects
b. | decay of radioactive element isotopes
c. | Both of the above
d. | None of the above.  Newly formed planets remain solid inside

ANS:	C	PTS:	1

	13.	The Jovian problem refers to
a. | the high speed with which the Jovian planets rotate on their axes.
b. | the large number of satellites that orbit each Jovian planet.
c. | the existence of rings around the Jovian planets.
d. | the excess heat radiated by the larger of the Jovian planets.
e. | the apparently short period of time that disks exist around stars from which Jovian planets can form.

ANS:	E	PTS:	1

	14.	____ pushed gas and dust particles out of the solar nebula by the light from the sun.
a. | Radiation pressure
b. | Outgassing
c. | Condensation
d. | Accretion
e. | Differentiation

ANS:	A	PTS:	1

	15.	Accretion is
a. | the adding of material to an object an atom or molecule at a time.
b. | the adding of material to an object by collection of solid particles.
c. | the release of gas from rocks as they are heated.
d. | the largest of the Galilean satellites.
e. | caused by the bombardment of the solar wind.

ANS:	B	PTS:	1

	16.	Outgassing is
a. | the adding of material to an object an atom or molecule at a time.
b. | the adding of material to an object by collection of solid particles.
c. | the release of gas from rocks as they are heated.
d. | the largest of the Galilean satellites.
e. | caused by the bombardment of the solar wind.

ANS:	C	PTS:	1

	17.	Which one of the following IS a characteristic of Jovian planets?
a. | low average density
b. | orbits inside the asteroids
c. | craters in old surfaces
d. | small diameters
e. | very few satellites

ANS:	A	PTS:	1

	18.	Which one of the following IS NOT a characteristic of terrestrial planets?
a. | low average density
b. | orbits inside the asteroids
c. | craters in old surfaces
d. | small diameters
e. | very few satellites

ANS:	A	PTS:	1

	19.	A future news release might report that a new planet has been found around a star very similar to our sun. This newly discovered planet is claimed to have a mass 40 times that of Earth and is located nearly 25 AU from the star it orbits. Which of the following would be a reasonable prediction about this planet?

I. | The planet will probably have a mean density of around 5 g/cm^3.
II. | The planet will probably have a radius of around five to ten times greater than Earth's.
III. | The planet will probably have several satellites.
IV. | The planet will probably have a composition that is mostly hydrogen and helium.

a. | I & IV
b. | I, II, & III
c. | II, III, & IV
d. | I, II, & IV
e. | I, II, III, & IV

ANS:	C	PTS:	1

	20.	A(n) ____ is a solar system object that enters Earth's atmosphere and becomes very hot due to friction between the object and Earth's atmosphere and does not survive to reach the surface.
a. | asteroid
b. | meteor
c. | comet
d. | meteoroid
e. | planetesimal

ANS:	B	PTS:	1

	21.	The age of the solar system is believed to be approximately 4.6 billion years based on the data from
a. | samples of lunar rocks.
b. | samples of Earth rocks.
c. | samples of meteorites.
d. | all of the above
e. | none of the above

ANS:	D	PTS:	1

	22.	Once a terrestrial planet had formed from a large number of planetesimals, heat could have melted it and allowed it to differentiate into metallic core of ____density and a rocky mantle or crust of ______ density.
a. | higher; lower
b. | lower; higher
c. | Wrong!  The interior stays solid
d. | Wrong!  There is no separation according to density.

ANS:	A	PTS:	1

	23.	The condensation sequence suggests that ____ should condense as solids closest to the sun.
a. | hydrogen and helium
b. | metals and metal oxides
c. | silicates
d. | ices of water, methane, and ammonia

ANS:	B	PTS:	1

	24.	Condensation in the solar nebula probably led to the formation of
a. | icy grains beyond the present orbit of Jupiter.
b. | metallic grains near the present orbit of Mercury.
c. | silicate grains near the present orbit of Earth.
d. | all of the above
e. | none of the above

ANS:	D	PTS:	1

	25.	Protoplanets of the Jovian planets could have grown very hot from
a. | heat for the sun.
b. | radioactivity of light elements such as hydrogen and helium.
c. | the in fall of material at high velocity.
d. | tidal forces due to the sun.
e. | collisions with large planetesimals.

ANS:	C	PTS:	1

	26.	The terrestrial planets are thought to have formed by accreting solid planetesimals all with about the same composition. This means
a. | they were initially molten forming an iron core first, then they accreted a silicate crust later.
b. | they were initially molten forming a silicate core first, then they accreted an iron crust later.
c. | they were initially collections of solid particles which melted then differentiated into a high density iron metal core and low density silicate crust.
d. | they were initially collections of solid particles which melted then differentiated into a high density silicate core and low density iron metal crust.

ANS:	C	PTS:	1

	27.	The planets all lie in nearly the same plane resulting in a disk-like structure for the solar system. This disk-like structure is believed to exist because
a. | the solar nebula from which the planets formed had a disk-like structure.
b. | the bipolar flow from the young sun cleared all material out of the nebula except that in the disk.
c. | Jupiter's gravity was great enough to pull all of the other planets to the plane of its orbit.
d. | the Milky Way Galaxy from which the planets condensed has a disk like structure

ANS:	A	PTS:	1

	28.	Which one of the following objects is most like the planetesimals that formed in the solar nebula?
a. | asteroids
b. | Earth
c. | Saturn
d. | Venus
e. | the sun

ANS:	A	PTS:	1

	29.	The large planetesimals would have grown faster than the smaller planetesimals because
a. | they were moving faster in their orbits than the smaller planetesimals.
b. | their stronger gravity would pull in more material.
c. | there was more material located near them that could be accreted.
d. | the smaller planetesimals were covered by a layer of material that was lost during collisions.
e. | all of the above

ANS:	B	PTS:	1

	30.	Accretion among the grains in the solar nebula would have been aided by
a. | static electricity.
b. | gravity.
c. | high-velocity collisions.
d. | all of the above
e. | none of the above

ANS:	A	PTS:	1

	31.	Based on current observations, ____ has a heavy element core, and a very compressed liquid layer and atmosphere both made mostly of hydrogen.
a. | Jupiter
b. | Pluto
c. | Venus
d. | an asteroid
e. | a meteor

ANS:	A	PTS:	1

	32.	If a star is found with five planets orbiting it, and a process like that described in the solar nebula theory formed the planets, which of the planets would be expected to have the greatest uncompressed density?
a. | The one farthest from the star.
b. | The one with the greatest mass.
c. | The one with the greatest radius.
d. | The one closest to the star.
e. | The one that has liquid water on its surface.

ANS:	D	PTS:	1

	33.	Part of the current atmosphere of Earth is believed to be
a. | the remnants of the original  hydrogen and helium gas from the solar nebula attracted by the protoplanet.
b. | the result of the melting and vaporizing of the glaciers from the last ice age.
c. | composed primarily of hydrogen and helium.
d. | composed of gases that were outgassed from the heated rocks sometime after the planet formed.
e. | the result of a collision between the sun and another star.

ANS:	D	PTS:	1

	34.	The most important effect in clearing the solar nebula of gas and dust was
a. | impacts by planetesimals.
b. | the solar wind.
c. | the sun's magnetic field.
d. | the asteroid belt.
e. | radiation pressure.

ANS:	E	PTS:	1

	35.	The uncompressed density of a planet in our solar system
a. | is greatest for the Jovian planets.
b. | is greatest for the planets closest to the sun.
c. | is greatest for the planets furthest from the sun.
d. | is greatest for the planets with the largest mass.
e. | is greatest of the planet with the largest radius.

ANS:	B	PTS:	1

	36.	51 Pegasi is important because
a. | it is a pulsar with planets orbiting around it.
b. | it is a star with a planet that is known to support intelligent life.
c. | it is the largest satellite of Jupiter.
d. | it is the largest known asteroid.
e. | it is the first star like our sun that was found to have a planet orbiting it.

ANS:	E	PTS:	1

	37.	On a photograph of the Earth’s moon, the moon measures 30 cm in diameter and a small crater measures 0.2 cm. The moon's physical diameter is 1738 km. What is the physical diameter of the small crater?
a. | about 1738 km
b. | about 12 km
c. | about 520 km
d. | about 350 km
e. | about 3.5 km

ANS:	B	PTS:	1

	38.	The speed of the solar wind is approximately 400 km/s and the distance from the sun to Saturn is 9.5 AU (1 AU = 1.5×10^8 km). How long does it take a particle in the solar wind to reach Saturn?
a. | about 4.1 hours
b. | about 4.1 days
c. | about 41 days
d. | about 4.1 years
e. | about 41 years

ANS:	C	PTS:	1

	39.	Suppose that Mercury grew to its present size in 1 million years through the accretion of particles averaging 100 g each. On average how many particles did Mercury capture each second? Note: Mercury has a mass of 3.3 × 10^23 kg and a radius of 2439 km.
a. | about 24 particles per second
b. | about 3.3 × 10^21 particles per second
c. | about 67 particles per second
d. | about 100 million particles per second
e. | about 100 billion particles per second

ANS:	E	PTS:	1

	40.	The diagram below illustrates the radioactive decay of Potassium (^40K), which has a half-life of 1.3 billion years. If a lunar rock is found that currently contains 5 grams of ^40K, and it is determined that the sample contained 20 grams when it was formed, how old is the lunar rock?

a. | 6.5 billion years
b. | 19.5 billion years
c. | 2.6 billion years
d. | 3.9 billion years
e. | 4.6 billion years

ANS:	C	PTS:	1

	41.	The solar nebula theory is NOT able to explain which of the following observed characteristics of the solar system?  Another theory would be needed.
a. | Common direction of rotation of the planets.
b. | Common direction of revolution of the planets.
c. | The formation of hydrogen atoms in the solar system from subatomic particles.
d. | The density of the Jovian planets.

ANS:	C	PTS:	1

	42.	What observation made of other stars seems to suggest the solar nebula hypothesis is correct?
a. | Stars are found to exist more often in binaries than by themselves.
b. | Protostars are seen to radiate much of their light at infrared wavelengths.
c. | Nearby stars tend to be low mass red dwarfs.
d. | Young stars are found to have hot disks that surround them.

ANS:	D	PTS:	1

	43.	Compared to the terrestrial planets, Jovian planets
a. | have a higher density.
b. | have a smaller number of moons.
c. | have a much larger diameter.
d. | are much hotter.

ANS:	C	PTS:	1

	44.	The asteroid belt is found between which two planets’ orbits?
a. | Earth and Mars
b. | Mars and Jupiter
c. | Jupiter and Saturn
d. | Venus and Earth

ANS:	B	PTS:	1

	45.	How is radioactive dating used to determine the age of an object?
a. | Both the amounts of radioactive and decay material are measured.  Using these with  the radioactive material’s  half-life, the age can be estimated.
b. | The amount of radioactive material is measured.  Using this with  the radioactive material’s  half-life, the age can be estimated.
c. | The amount of decay material is measured.  Using this with  the radioactive material’s  half-life, the age can be estimated.
d. | The amount of heat generated by radioactive dating is measured to determine age.

ANS:	A	PTS:	1

	46.	How is the presence of space debris accounted for by solar system models?
a. | Space debris is left over material from the early solar system that never formed into a planet.
b. | Space debris was formed by the collision of objects after the planets formed.
c. | Space debris is material that existed in our region of space before the sun formed.
d. | Both a and b
e. | All of the above

ANS:	D	PTS:	1

COMPLETION

	1.	The ____________________ planets have larger radii than the ____________________ planets.

ANS:	Jovian, terrestrial

PTS:	1

	2.	The adding of material an atom at a time to create  a solid grain or flake is the process of ____________________.

ANS:	condensation

PTS:	1

	3.	The description large somewhat dirty snowball model fits the physical structure of ____________________.

ANS:	comets

PTS:	1

	4.	The diagram below shows the radioactive decay of cesium (^135Cs). What is the half-life of ^135Cs?

ANS:	3 million years

PTS:	1

	5.	The ____________________ of a radioactive substance is the amount of time for the substance to be reduced by half.

ANS:	half-life

PTS:	1

	6.	A planet found orbiting a star other than the sun is called a(n) ____________________.

ANS:	extrasolar

PTS:	1

TRUE/FALSE

	1.	The oldest objects found so far in our solar system are Earth rocks that are 3.9 billion years old.

ANS:	F	PTS:	1

	2.	The Jovian planets have lower average densities than the terrestrial planets.

ANS:	T	PTS:	1

	3.	The original cloud from which the sun and planets formed had a composition rich in hydrogen and helium.

ANS:	T	PTS:	1

	4.	The present motions of the planets were inherited from the rotation of the solar nebula.

ANS:	T	PTS:	1

	5.	The condensation sequence cannot explain the composition of the terrestrial and Jovian planets.

ANS:	F	PTS:	1

	6.	When particles in the solar nebula grew large enough, they stopped growing by accretion and began growing by condensation.

ANS:	F	PTS:	1

	7.	Observations in the infrared have detected dusty nebulae around T Tauri stars.

ANS:	T	PTS:	1

	8.	Outgassing refers to the formation of an atmosphere by the attraction of gases from the surrounding nebula.

ANS:	F	PTS:	1

	9.	The pressure of sunlight was one of the forces that cleared the solar nebula.

ANS:	T	PTS:	1

ESSAY

	1.	How do the motions of the sun and planets reflect the disk shape of the solar nebula?

ANS:	
Answer not provided.

PTS:	1

	2.	Which are the oldest solar system objects that have been dated radioactively? What are their ages?

ANS:	
Answer not provided.

PTS:	1

	3.	What observational evidence do we have that nebulae from which planets could form surround other stars?

ANS:	
Answer not provided.

PTS:	1

	4.	How does the solar nebula theory explain the present densities and chemical compositions of the planets?

ANS:	
Answer not provided.

PTS:	1

	5.	How did differentiation and outgassing alter protoplanets?

ANS:	
Answer not provided.

PTS:	1

	6.	Describe four effects that helped to clear the solar nebula.

ANS:	
Answer not provided.

PTS:	1

	7.	How does the solar nebula theory account for the presence of comets?

ANS:	
Answer not provided.

PTS:	1

	8.	Describe some characteristics that all the planets seem to share and use the solar nebula theory to explain them.

ANS:	
Answer not provided.

PTS:	1