Deck 12: Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Question 1

How does the largest asteroid,Ceres,compare in size to other solar system worlds?

A)It is larger than Pluto and Mercury.
B)It is about the size of a large jovian moon.
C)It is about the size of Pluto.
D)It is about a quarter the size of the Moon.
E)It is smaller than any jovian moon.

Answer 1

D

Question 2

Where are the Trojan asteroids located?

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

Answer 2

B

Question 3

Why isn't there a planet where the asteroid belt is located?

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

Answer 3

C

Question 4

The combined mass of all the asteroids in the asteroid belt is

A)less than that of any terrestrial planet.
B)about the same as that of Earth.
C)about twice that of Earth.
D)about the same as that of Jupiter.
E)more than that of all the planets combined.

Question 5

A rocky leftover planetesimal orbiting the Sun is

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

Question 6

The large gaps in the asteroid belt (often called Kirkwood gaps)are caused by

A)large asteroids that clear certain regions of the asteroid belt.
B)tidal forces from Jupiter.
C)tidal forces from the Sun.
D)orbital resonances with Jupiter.
E)the competing gravitational tugs of Mars and Jupiter.

Question 7

What do we call a small piece of solar system debris found on Earth?

A)solar system debris
B)cometary fragment
C)meteor
D)meteorite
E)meteoroid

Question 8

Which is closest to the average distance between asteroids in the asteroid belt?

A)1 thousand km
B)10 thousand km
C)100 thousand km
D)1 million km
E)10 million km

Question 9

An icy leftover planetesimal orbiting the Sun is

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

Question 10

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 similar orbital radii.
D)They have a similar range of orbital inclinations.
E)They have nothing in common with each other.

Question 11

How can we determine an asteroid's reflectivity?

A)by determining its mass
B)by comparing its infrared thermal emission to its visible-light reflection
C)by seeing how dark or light it looks in telescopic images
D)by determining how far from the Sun it is
E)by determining its size

Question 12

If we know the size of an asteroid,we can determine its density by

A)comparing its reflectivity to the amount of light it reflects.
B)looking for brightness variations as it rotates.
C)determining its mass from its gravitational pull on a spacecraft,satellite,or planet.
D)radar mapping.
E)spectroscopic imaging.

Question 13

What is a meteorite?

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

Question 14

What is the size of the largest asteroid?

A)1 km
B)10 km
C)100 km
D)1,000 km
E)10,000 km

Question 15

Why aren't small asteroids spherical in shape?

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

Question 16

Why do asteroids and comets differ in composition?

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

Question 17

We know that there are large gaps in the average distances of asteroids from the Sun (within the asteroid belt)because we

A)see the gaps through telescopes.
B)see the gaps via stellar occultation.
C)know they are there theoretically,although we haven't detected them.
D)actually don't know whether there really are gaps or not.
E)have plotted distributions of the orbital radii of the asteroids.

Question 18

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

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

Question 19

A typical shooting star in a meteor shower is caused by a ________ entering Earth's atmosphere.

A)boulder-size particle from an asteroid
B)boulder-size particle from a comet
C)pea-size particle from an asteroid
D)pea-size particle from a comet
E)microscopic particle of interstellar dust

Question 20

Which of the following statements about comets and asteroids is true?

A)Only asteroids collide with Earth.
B)Comets are balls of ice and dust.
C)Most of the trillions of comets in our solar system have tails.
D)All asteroids lie in the asteroid belt between Mars and Jupiter.
E)There are about 1 million known asteroids in the solar system.

Question 21

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

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

Question 22

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

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

Question 23

When was Pluto discovered?

A)about 30 years ago
B)about 80 years ago
C)about 200 years ago
D)about 2000 years ago
E)in ancient history

Question 24

Primitive meteorites can be distinguished from other meteorites and terrestrial rocks because they

A)contain a noticeable fraction of pure metallic flakes.
B)resemble the composition of Earth's core.
C)contain a lot of iron and were used by humans to make iron tools.
D)resemble the composition of Earth's mantle.
E)resemble the composition of rocks from lava flows that occurred on asteroids very shortly after the formation of the solar system.

Question 25

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

A)Pluto has a cometlike composition and density.
B)Pluto is regarded by many to be a planet.
C)Some asteroids have their own moons.
D)Pluto has a more eccentric orbit than other planets.
E)Some known Kuiper-belt objects are hundreds of kilometers across.

Question 26

In the asteroid impact theory of the extinction of the dinosaurs some 65 million years ago,the dinosaurs (and over half of all the other species on Earth at that time)died off largely because

A)of injuries suffered from direct hits of pieces of the asteroid or comet.
B)dust injected into the stratosphere from the impact absorbed visible light from the Sun,causing global temperatures to plummet.
C)radiation from iridium in the asteroid caused the dinosaurs to die of cancer.
D)the impact caused massive earthquakes and volcanic activity worldwide.
E)dust settled on the leaves of plants,making them inedible,so the animals died of starvation.

Question 27

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

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

Question 28

Processed meteorites with low metal content probably are

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

Question 29

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

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

Question 30

In order to have a comet named after you,you have to

A)calculate its orbit and predict when it will return.
B)publish a picture of it in an astronomical journal.
C)be one of the first three discoverers who report it to the International Astronomical Union (IAU).
D)be a well-known astronomer.
E)be and do all of the above

Question 31

Most meteorites are

A)carbon-rich and primitive.
B)rocky and primitive.
C)carbon-rich and processed.
D)rocky and processed.
E)iron-rich and processed.

Question 32

Halley's comet is named after the English scientist Edmund Halley because he

A)discovered it.
B)was the first to see it in 1682.
C)calculated its orbit and predicted that it would return in 1758.
D)was the most famous astronomer in England during its appearance.
E)was the first to publish pictures of it and report it to the International Astronomical Union (IAU).

Question 33

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

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

Question 34

The number of comets in the Oort cloud is probably about

A)a thousand.
B)a million.
C)a billion.
D)a trillion.
E)a quintillion.

Question 35

Why won't Pluto collide with Neptune?

A)Pluto's orbit is completely outside Neptune's orbit.
B)Pluto's orbit is completely inside Neptune's orbit.
C)Pluto's orbit never comes anywhere close to Neptune's orbit.
D)The two planets have an orbital resonance that prevents them from colliding.
E)It could!

Question 36

Meteorites can come from

A)the cores of asteroids.
B)the Moon.
C)Mars.
D)comets.
E)all of the above

Question 37

When do comets generally begin to form a tail?

A)inside Mercury's orbit
B)between Mercury and Earth's orbit
C)beyond Jupiter's orbit
D)inside of Jupiter's orbit
E)They always have a tail (until they run out of material).

Question 38

What is Charon?

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

Question 39

What characteristic distinguishes a meteorite from a terrestrial rock?

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

Question 40

What is the typical size of comets that enter the inner solar system?

A)1 km
B)10 km
C)100 km
D)1000 km
E)Comet sizes are unknown because their tails obscure the nucleus.

Question 41

Comet nuclei can be darker than charcoal.

Question 42

Comets appear to race across the sky in photographs,but in reality they remain nearly stationary relative to the stars.

Question 43

A comet that has an orbit around the Sun inclined to the ecliptic plane by 65° probably originated in the Kuiper belt.

Question 44

A spacecraft traveling through the asteroid belt has a high risk of being destroyed through a collision.

Question 45

Process of Science: Observations of asteroids,comets,and meteorites help refine the theory of the formation of the solar system.

Question 46

All asteroids are spherical solid objects,similar to the Moon and Mercury,just much smaller.

Question 47

Pluto's gravity affects the orbit of Uranus,and this fact was used to discover Pluto.

Question 48

All meteorites collected on Earth come from asteroids or comets.

Question 49

The word "comet" comes from the Greek word for which of the following?

A)bright
B)hair
C)fuzzy
D)tail

Question 50

Viewed from Pluto,the Sun would appear more than a thousand times fainter than on Earth.

Question 51

Falling stars and shooting stars are simply other names for meteors.

Question 52

On average,how often do impactors about 10 km in size,large enough to produce mass extinction,hit Earth?

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

Question 53

No spacecraft has ever visited an asteroid or comet.

Question 54

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 direct proof that impacts really occur.
D)It confirmed our theory of solar system formation.
E)It was the first event in modern history that was brighter than the full moon in the sky.

Question 55

The total mass of the Kuiper belt is greater than that of the asteroid belt.

Question 56

Pluto is the largest Kuiper Belt Object.

Question 57

Which of the following Pluto observations did not help convince scientists to change Pluto's status from that of a planet?

A)discovery of the Kuiper Belt
B)discovery of seasonal atmosphere,similar to comets
C)discovery of large Kuiper Belt Objects
D)discovery of Pluto's 5 moons

Question 58

Describe at least three ways in which our solar system would be different if orbital resonances had never been important.

Question 59

Most meteorites collected on Earth are of the rocky primitive variety,although most asteroids are of the carbon-rich variety.

Question 60

Oort-cloud comets are so far from the Sun that the gravity of neighboring stars can alter their orbits.

Question 61

In what ways is Pluto like other Kuiper-belt objects?

Question 62

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

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

Question 63

Which statement about asteroids is not true?

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

Question 64

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

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

Question 65

Briefly describe the evidence suggesting that a 10-km asteroid or comet hit Earth at the time of the dinosaur extinction.

Question 66

Explain how astronomers determine the size of an asteroid without resolving it.

Question 67

Process of Science: Explain how observations of asteroids,comets,and meteorites test our theory for the formation of the solar system in unique ways that are not possible through observations of the planets.

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 Oort cloud contain large proportions of ice.
D)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.

Question 69

What do we mean by a primitive meteorite?

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

Question 70

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

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

Question 71

The asteroid belt is located

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

Question 72

Describe some ways in which a meteorite can be distinguished from a terrestrial rock.

Question 73

Why would anyone be interested in mining material from an asteroid?

Question 74

Process of Science: Why did astronomers identify Pluto as a planet from its discovery? What scientific evidence led to its reclassification?

Question 75

How are asteroid masses measured?

Question 76

Why is the Kuiper belt flat but the Oort cloud spherical?

Question 77

Dawn images of Vesta show that it is much wider than it is tall.What might be the reason for its irregular shape?

Question 78

What evidence do we have of geological activity on asteroids in the past?

Question 79

Briefly describe how an impact could lead to a mass extinction.

Question 80

Why are most meteorites found in Antarctica?