Deck 9: Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Question 1

What do asteroids and comets have in common?

A)Most are unchanged since their formation in the solar nebula.
B)They have similar densities.
C)They have a similar range of orbital inclinations.
D)They have similar orbital radii.
E)They have nothing in common with each other.

Answer 1

A

Question 2

Pluto is most like a

A)comet.
B)star.
C)jovian (gas giant)planet.
D)terrestrial planet.

Answer 2

A

Question 3

What do we mean by a mass extinction?

A)an extinction caused by the impact of an asteroid or comet
B)the extinction of a large fraction of the world's plant and animal species in a relatively short period of time
C)the extinction of any species of plant or animal that has mass
D)the extinction of large animals, such as dinosaurs

Answer 3

B

Question 4

What evidence led astronomers to conclude that the Oort cloud is a spherical distribution of comets?

A)direct observation of comets orbiting the sun in the Oort cloud
B)the observation that comets enter the solar system from random directions
C)Astronomers did not draw that conclusion; the Oort cloud is shaped like a flat ring in the same plane as the planets.

Question 5

An icy leftover planetesimal orbiting the Sun is

A)a comet.
B)a meteorite.
C)a meteor.
D)an asteroid.
E)possibly any of the above

Question 6

Why didn't a planet form where the asteroid belt is now located?

A)There was too much rocky material to form a terrestrial planet, but not enough gaseous material to form a jovian planet.
B)There was not enough material in this part of the solar nebula to form a planet.
C)The temperature in this portion of the solar nebula was just right to prevent rock from sticking together.
D)Gravitational tugs from Jupiter prevented material from collecting together to form a planet.

Question 7

In what way(s)does this figure give a poor representation of the asteroid belt?

A)The image does not show the vertical distribution of asteroids relative to the ecliptic plane.
B)For a correct scale, the asteroids should be drawn much smaller. This image gives the impression that the asteroid belt is very crowded.
C)It shows the positions of the asteroids at a mix of times.
D)A and B
E)A and C

Question 8

Assume that the average rate of 1- km sized asteroids hitting the Earth is about 1 every million years. The chance of the Earth being hit by a 1- km sized asteroid in the next 100 years is about:

A)inevitable, it has to happen sometime.
B)zero.
C)one in ten thousand.
D)one in a million.
E)one in 100 million.

Question 9

Which of the following is not a piece of evidence supporting the idea that an impact caused the mass extinction that occurred 65 million years ago?

A)Grains of quartz formed under high pressure are found in a layer of clay that dates to 65 million years ago.
B)Unusually large abundances of iridium and other rare metals are found in a layer of clay that dates to 65 million years ago.
C)A large impact crater along the coast of Mexico dates to 65 million years ago.
D)Fossilized dinosaur bones contain fragments of rock from the impact.

Question 10

Which of the following is furthest from the Sun?

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

Question 11

What do astronomers mean when they refer to "gaps" in the asteroid belt between Mars and Jupiter?

A)There are very few asteroids with diameters between 1 and 100 kilometers, creating a "gap" in the size distribution.
B)There is a large population of asteroids too faint to see called the "gap" asteroids.
C)Asteroids typically cluster together and this creates "gaps" on the sky.
D)There are either pure metal or pure rock asteroids, but no mixtures. Thus there is a "gap" in the composition of asteroids.
E)Asteroids seem to avoid certain orbits around the Sun, creating "gaps" in the orbits that asteroids can have.

Question 12

The greatest number of asteroids are found

A)between 4 and 5 AU from the sun.
B)between 3 and 4 AU from the sun.
C)between 1 and 2 AU from the sun.
D)between 2 and 3 AU from the sun.

Question 13

According to the nebular theory, how did the asteroid belt form?

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

Question 14

According to current evidence, Pluto is best explained as .

A)a large member of the Kuiper belt
B)an escaped moon of Jupiter or Saturn
C)a terrestrial planet that is surprisingly far from the Sun
D)a very small jovian planet

Question 15

Why do asteroids and comets differ in composition?

A)Asteroids formed inside the frost line, while comets formed outside.
B)Asteroids are much larger than comets.
C)Asteroids and comets formed at different times.
D)Comets are much larger than asteroids.
E)Comets formed from the jovian nebula, while asteroids did not.

Question 16

What part of a comet always points most directly away from the Sun?

A)the nucleus
B)the jets of gas
C)the coma
D)the dust tail
E)the plasma tail

Question 17

What happened to the "Impactor" of the Deep Impact mission?

A)It missed the comet altogether.
B)It landed safely on the surface of the comet and returned material to Earth.
C)It blasted straight through the comet leaving a small hole.
D)It blasted the comet apart, thus preventing a potential Earth collision.
E)It created a small crater on the comet.

Question 18

Among discovered meteorites, we have found some with all the following origins except .

A)being a fragment of a shattered asteroid
B)being a fragment from the surface of the Moon
C)being a fragment from Comet Halley
D)being a fragment from the surface of Mars

Question 19

How frequently do objects that threaten widespread devastation hit the Earth?

A)about once every thousand years
B)about once every million years
C)about once every year
D)about once every hundred million years

Question 20

What is Eris?

A)the largest known asteroid
B)a moon of Pluto
C)an extrasolar planet ejected by another solar system and captured by ours
D)an icy object that orbits in the Kuiper belt and is larger than Pluto

Question 21

What is Tunguska?

A)a postulated binary companion to the Sun thought to be responsible for mass extinctions
B)a long period comet that struck Jupiter in 1994
C)a newly discovered moon of Pluto
D)the site of an asteroid impact that occurred in Siberia in 1908
E)the Gulf of Mexico basin that is the crater of the asteroid impact that caused the mass extinction of the dinosaurs 65 million years ago

Question 22

What is Eris?

A)the largest known Kuiper Belt object
B)the largest known asteroid
C)the largest known extrasolar planet
D)the largest moon of Saturn
E)Pluto's largest moon

Question 23

Which of the following is not a piece of evidence supporting the idea that Pluto is a large comet of the Kuiper belt?

A)Pluto is not the largest object orbiting in the region of the Kuiper belt.
B)Pluto's orbit is very similar to the orbits of other known Kuiper belt comets.
C)Triton, which must once have orbited the Sun before being captured by Neptune, is significantly larger than Pluto.
D)Pluto's composition appears to match that of other known Kuiper belt comets.
E)Pluto grows a coma and a long tail when it is at the point in its orbit closest to the Sun.

Question 24

If a major asteroid collision in the asteroid belt occurs, on average, 1 time in 100,000 years, then how many major collisions have occurred over the approximately 4 billion year history of the solar system?

A)about 4,000
B)about 4 billion
C)about 4 million
D)about 40,000

Question 25

The last major dinosaurs were wiped out as a consequence of a major impact with the Earth about 65 million years ago. All but one of the following statements would be regarded as evidence for this claim.

A)The fossil record shows a mass extinction event 65 million years ago, where only 25% of the species survived.
B)At least 150 craters from past impacts have been identified, including one of the right age and size in Mexico.
C)A layer of iridium in 65- million year old sediments in the Earth's crust
D)Multiple historical accounts describe a planetary- level flood and storm that wiped out most living things.

Question 26

How do asteroids appear in long exposure images?

A)as points of light, like the stars
B)as complex curving and looping lines
C)as resolved disks, like the planets
D)as straight lines across a background of stars

Question 27

Which statement about asteroids is not true?

A)Most asteroids are not spherical in shape.
B)Some are more like loosely bound piles of rubble than solid chunks of rock.
C)Many, but not all, orbit the Sun in the asteroid belt.
D)If we could put all the asteroids together, they would make an object about the size of Earth.

Question 28

In what way(s)has Pluto long been known to be different from the planets?

A)It is composed primarily of ices.
B)It is far smaller than the terrestrial planets.
C)It has a highly eccentric orbit.
D)Its orbit is more inclined to the ecliptic plane.
E)All of the above

Question 29

Where did comets that are now in the Kuiper belt originally form?

A)inside Jupiter's orbit
B)in the asteroid belt
C)between the orbits of Jupiter and Neptune
D)in the Oort cloud
E)near the radius at which they orbit today

Question 30

During the time that a comet passes through the inner solar system, the comet can appear quite bright because

A)sunlight reflects off the comet's tail and coma.
B)increasing friction causes the comet's nucleus to glow.
C)sunlight reflects off the comet's nucleus.
D)heat from the Sun causes the comet's nucleus to glow.

Question 31

Suppose we discover a new comet on an orbit that brings it closer to the Sun than Mercury every 125 years. What can we conclude?

A)It has been on its current orbit for only a very short time compared to the age of our solar system.
B)It has a coma and tail during most of each orbit.
C)It came from the Oort cloud.
D)It came from the Kuiper belt.

Question 32

How was Pluto's surface mapped?

A)by measuring the change in brightness as Charon eclipsed Pluto
B)by imaging with powerful ground based telescopes
C)by imaging with the Hubble Space Telescope
D)by mapping with the New Horizons spacecraft
E)Pluto is too far away for its surface to be mapped.

Question 33

What was the Shoemaker- Levy 9 impact?

A)the ninth impact witnessed by astronomers in modern times
B)the impact that created the Moon's largest crater
C)the 1994 impact of a chain of comet fragments into Jupiter
D)the impact thought to have wiped out the dinosaurs

Question 34

Which of the following objects are probably not located in the same general region of the solar system in which they originally formed?

A)Pluto
B)Kuiper belt comets
C)asteroids of the asteroid belt
D)Oort cloud comets

Question 35

Will Pluto eventually collide with Neptune?

A)No, because Pluto's orbit is completely outside Neptune's orbit.
B)No, because Pluto's orbit is completely inside Neptune's orbit.
C)Yes.
D)No, because the two planets have an orbital resonance that prevents them from colliding.
E)No, because Pluto's orbit never comes anywhere close to Neptune's orbit.

Question 36

Suppose you find a meteorite made almost entirely of metal. According to current science, which of the following statements must be true?

A)Your meteorite was blasted off the surface of Mars by an impact.
B)Your meteorite is a fragment of an object from the Kuiper belt.
C)Your meteorite is a fragment from the core of a large asteroid that shattered in a collision.
D)Radiometric dating will show the age of your meteorite to date to the formation of our solar system.

Question 37

What is a meteorite?

A)a streak of light caused by a star moving across the sky
B)a comet that burns up in Earth's atmosphere
C)a fragment of an asteroid from the solar system that has fallen to Earth's surface
D)a streak of light caused by a small particle from space burning up in Earth's atmosphere
E)a small moon that orbits one of the giant planets

Question 38

Why do we sometimes observe asteroids at the distances of the gaps in the asteroid belt?

A)They are kept in place by shepherding asteroids.
B)A gap is located at an average orbital distance, and asteroid orbits often have large eccentricities.
C)Jupiter's gravitational tugs keep them there.
D)They are held in place by resonances with other asteroids.
E)Actually, we never see asteroids in the gaps.

Question 39

What lucky factor prevented the Chelyabinsk object from causing much damage at ground level?

A)It was made entirely of ices and thus exploded high in the air.
B)It hit Earth at an oblique angle and thus exploded high in the air.
C)A prototype asteroid defense system was being tested nearby.

Question 40

If all the asteroids were gathered into a single object, it would make an object

A)about the size of the Earth.
B)with enough mass to gather hydrogen and helium and become a gas giant.
C)about half the diameter of Earth's moon.
D)about the size of Earth's moon.

Question 41

The discovery of Eris .

A)was not surprising, because other Kuiper belt objects approaching the size of Pluto had already been discovered
B)was not surprising, because the existence of a massive "Planet X" had been predicted nearly a century ago
C)was surprising, due to its "backwards" orbit around the Sun
D)was surprising, since we thought we knew about all large objects in the solar system

Question 42

What do we mean by a primitive meteorite?

A)a piece of rock that is essentially unchanged since it first condensed and accreted in the solar nebula some 4.6 billion years ago
B)a meteorite that fell to Earth at least 4 billion years ago
C)a type of meteorite that is usually made mostly of high- density metals
D)a meteorite that was discovered by primitive people

Question 43

What is Charon?

A)the largest known asteroid
B)the largest known Kuiper belt object
C)a captured moon of Neptune
D)the largest of Pluto's five known moons

Question 44

According to the nebular theory, how did the Kuiper belt form?

A)It consists of objects that fragmented from the protosun during a catastrophic collision early in the formation of the solar system.
B)It is made of planetesimals between the orbits of Mars and Jupiter that never formed into a planet.
C)It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form 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 is made of planetesimals formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets.

Question 45

Where are the Trojan asteroids located?

A)along Jupiter's orbit, 60° ahead of and behind Jupiter
B)on orbits that cross Earth's orbit
C)in the center of the asteroid belt
D)on orbits that cross Mars's orbit
E)surrounding Jupiter

Question 46

Why won't Pluto collide with Neptune?

A)Pluto orbits the Sun exactly two times for every three Neptune orbits, which ensures they never come close together.
B)Pluto is always much farther from the Sun than Neptune.
C)Actually, a collision of the two is inevitable within the next billion years.
D)Pluto's orbit never comes anywhere close to Neptune's orbit.

Question 47

Gaps in the asteroid belt (often called Kirkwood gaps)are caused by .

A)tidal forces from Jupiter
B)the competing gravitational tugs of Mars and Jupiter
C)orbital resonances with Jupiter
D)tidal forces from the Sun

Question 48

When a comet passes near the Sun, part of it takes on the appearance of a large, bright ball from which the tail extends. This part is called _.

A)the nucleus
B)the plasma tail
C)the Oort core
D)the coma

Question 49

What is the name of the largest known Kuiper Belt Object?

A)Sedna
B)Eris
C)Charon
D)Quaoar
E)Pluto

Question 50

A rocky leftover planetesimal orbiting the Sun is

A)a meteorite.
B)a meteor.
C)an asteroid.
D)a comet.
E)possibly any of the above

Question 51

Processed meteorites with high metal content probably are

A)leftover chunks of rock from the earliest period in the formation of the solar system.
B)chunks of rock chipped off the planet Mars.
C)pieces of comets rather than of asteroids.
D)chunks of the core of a larger asteroid that was shattered by a collision.
E)chunks of rock chipped off the planet Mercury.

Question 52

A typical meteor is created by a particle about the size of a .

A)baseball
B)pea
C)basketball
D)car

Question 53

Suppose that large jovian planets had never formed in our solar system. Which of the following would most likely be true?

A)Earth would orbit much closer to the Sun.
B)Neither the asteroid belt nor Oort cloud would exist.
C)There would be a large empty region in our solar system between the orbit of Mars and the Kuiper belt.
D)Earth would have suffered far fewer impacts.

Question 54

What is Pluto's moon Charon thought to have in common with our own Moon?

A)It has the same basic composition.
B)It probably formed as a result of a giant impact.
C)It has the same approximate mass.
D)It has the same average density.

Question 55

How many moons is Pluto known to have?

A)four
B)three
C)none
D)two
E)one

Question 56

Which of the following does not lend support to the idea that Pluto is a Kuiper- belt object?

A)Pluto is smaller than many known comets, such as Halley's comet.
B)Pluto has a comet- like composition and density.
C)Pluto has a more eccentric orbit than other planets.
D)Some known Kuiper- belt objects are hundreds of kilometers across.
E)Some Kuiper- belt objects have their own moons.

Question 57

Why aren't small asteroids spherical in shape?

A)Large asteroids became spherical because many small collisions chipped off pieces until only a sphere was left; this did not occur with small asteroids.
B)Small asteroids have odd shapes because they were all chipped off larger objects.
C)The strength of gravity on small asteroids is less than the strength of the rock.
D)Large asteroids were once molten and therefore became spherical, but small asteroids were never molten.

Question 58

Comets with extremely elliptical orbits, like Hyakutake and Hale- Bopp,

A)are captured by Jupiter.
B)come from the asteroid belt.
C)are Trojan comets.
D)come from the Kuiper belt.
E)come from the Oort cloud.

Question 59

How do asteroids differ from comets?

A)Asteroids and comets are both made of rocky and icy material, but asteroids are smaller in size than comets.
B)Asteroids and comets are both made of rocky and icy material, but asteroids are larger in size than comets.
C)Asteroids are made of icy material. Comets are made of rocky material.
D)Asteroids are made of rocky material. Comets are made of icy material.

Question 60

Which statement is not thought to be true of all comets in our solar system?

A)All comets are leftover planetesimals that originally condensed beyond the frost line in the solar nebula.
B)All comets are icy in composition.
C)Comets always have tails.
D)All comets orbit the Sun.

Question 61

Where did comets that are now in the Oort cloud originally form?

A)near the jovian planets
B)within the solar nebula, but far outside the orbit of Pluto
C)outside Neptune's orbit
D)inside Jupiter's orbit
E)all of the above

Question 62

What would be the consequence(s)of more frequent collisions between planets and asteroids?

A)We would find more Martian meteorites on Earth.
B)We would observe more meteor showers.
C)Earth and other planets would have more large craters.
D)A and B
E)A and C

Question 63

What was the Stardust mission?

A)a mission to study the composition of an asteroid by hitting it with a massive object and observing the material thrown into space
B)a mission to study the outer planets of the solar system by sending a probe from one to the next with a wide variety of instruments
C)a mission to study the composition of a comet by collecting material from its tail and return that material to Earth
D)a mission to study the surface structure of a comet by dropping a lander onto its surface

Question 64

A rock found on Earth that crashed down from space is called .

A)an asteroid
B)a meteorite
C)an impact
D)a meteor

Question 65

The total number of comets orbiting the Sun is estimated to be about .

A)1 million
B)1 trillion
C)100,000
D)1,000

Question 66

Suppose there were no solar wind. How would the appearance of a comet in our inner solar system be different?

A)It would not have a nucleus.
B)It would be much brighter in appearance.
C)It would have only one tail instead of two.
D)It would not have a coma.

Question 67

What is Charon?

A)the largest known comet
B)Pluto's largest moon
C)one of the Galilean moons of Jupiter
D)the largest known asteroid
E)a moon of Neptune

Question 68

Which of the following statements is not true?

A)Objects in the asteroid belt are made mostly of rock and metal.
B)Objects in the Kuiper belt are made mostly of rock and metal.
C)Objects in the asteroid belt and Kuiper belt orbit the Sun in nearly the same plane as the planets, but objects in the Oort cloud do not.
D)Objects in the Oort cloud contain large proportions of ice.

Question 69

What is the typical size of a comet's nucleus?

A)1000 km
B)10 km
C)1 meter
D)100 km
E)Sizes are unknown because the nucleus is obscured by the coma.

Question 70

If the hypothesis tracing the extinction of the dinosaurs to an impact is correct, the dinosaurs died off largely because .

A)the impact caused massive earthquakes worldwide
B)radiation from iridium in the asteroid caused the dinosaurs to die of cancer
C)of injuries suffered from direct hits of pieces of the asteroid or comet
D)of global climate effects initiated by dust and smoke that entered the atmosphere after the impact

Question 71

When you see the bright flash of a meteor, what are you actually seeing?

A)the glow from a pea- size particle and the surrounding air as the particle burns up in our atmosphere
B)emission of visible light from a particle that has not yet entered Earth's atmosphere
C)the flash that occurs when a speeding rock from space hits the ground
D)a star that has suddenly shot across the sky

Question 72

Meteorites can come from

A)the Moon.
B)the crusts and mantles of asteroids.
C)Mars.
D)the cores of asteroids.
E)all of the above

Question 73

The asteroid belt is located .

A)between the orbits of Jupiter and Saturn
B)beyond the orbit of Neptune
C)between the orbits of Mars and Jupiter
D)between the orbits of Earth and Mars

Question 74

Why was the Shoemaker- Levy 9 impact so important to astronomers?

A)It dredged up material that gave us our first direct look at Jupiter's interior composition.
B)It wiped out the dinosaurs.
C)It was the first event in modern history that was brighter than the full moon in the sky.
D)It was the first direct proof that impacts really occur.
E)It confirmed our theory of solar system formation.

Question 75

Kirkwood gaps in the asteroid belt occur at distances where

A)the orbit would take the asteroid beyond the "frost line" in the solar system.
B)the period of an orbiting asteroid would be the same as Jupiter's orbital period.
C)the density of asteroids is high enough for a large collision to pulverize a number of asteroids.
D)the period of an orbiting asteroid would be the same as Mars's orbital period.
E)the period of an orbiting asteroid would be a simple fraction (like 1/3 or 1/4)of Jupiter's orbital period.

Question 76

Why does the plasma tail of a comet always point away from the Sun?

A)Gases from the comet, heated by the Sun, push the tail away from the Sun.
B)The solar wind blows the plasma ions directly away from the Sun.
C)The conservation of the angular momentum of the tail keeps it always pointing away from the Sun.
D)It is allergic to sunlight.
E)Radiation pressure from the Sun's light pushes the ions away.

Question 77

On average, how often do impacts large enough to produce mass extinction on the Earth occur?

A)once in Earth's history
B)once every thousand years
C)once every hundred million years
D)once every million years
E)once every century

Question 78

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

A)It is made mostly of ices.
B)It formed outside of the frost line in the solar nebula.
C)It doesn't have rings.
D)Its orbit is not very close to being circular.
E)It has a solid surface.

Question 79

According to the nebular theory, how did the Oort cloud form?

A)It consists of objects that fragmented from the protosun during a catastrophic collision early in the formation of the solar system.
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 made of planetesimals formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets.
E)It is material left over from the interstellar cloud that never contracted with the rest of the gases to form the solar nebula.

Question 80

What characteristic distinguishes a meteorite from a terrestrial rock?

A)A meteorite usually has a high metal content.
B)Meteorites contain rare elements, such as iridium, that terrestrial rocks do not.
C)Meteorites have different isotope ratios of particular elements when compared to terrestrial rocks.
D)A meteorite is usually covered with a dark crust from burning in Earth's atmosphere.
E)All of the above are true.