Chapter 12 home work 8 Asteroids, Comets, and Dwarf Planets

Question 1

Which of the following statements is not true?

Objects in the Oort cloud contain large proportions of ice.
Objects in the asteroid belt are made mostly of rock and metal.
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.
Objects in the Kuiper belt are made mostly of rock and metal.

Answer 1

Objects in the Kuiper belt are made mostly of rock and metal.

Question 2

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

car
baseball
basketball
pea

Answer 2

pea

Question 3

What do we mean by a primitive meteorite?

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

Answer 3

a meteorite that is essentially unchanged since it first condensed and accreted in the solar nebula some 4.6 billion years ago

Question 4

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

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

Answer 4

Comets always have tails.

Question 5

Which direction do a comet’s dust and plasma tails point?

perpendicular to the ecliptic plane
generally away from the Sun
straight behind the comet in its orbit
always almost due north

Answer 5

generally away from the Sun

Question 6

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

1 million
1 trillion
1,000
100,000

Answer 6

1 trillion

Question 7

Halley’s comet is named after the English scientist Edmund Halley (1656–1742) because ______.

He was the first person to see it when it passed near Earth in 1682.
He was the most famous astronomer alive in England during its appearance in 1758.
He calculated its orbit and predicted the year in which it would next be seen.
The discoverers named it for him in honor of his financial support.

Answer 7

He calculated its orbit and predicted the year in which it would next be seen.

Question 8

According to current evidence, Pluto is best explained as ______.

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

Answer 8

a large member of the Kuiper belt

Question 9

What is Eris?

The largest known asteroid.
An icy object that orbits in the Kuiper belt and is larger than Pluto
An extrasolar planet ejected by another solar system and captured by ours.
A moon of Pluto.

Answer 9

An icy object that orbits in the Kuiper belt and is larger than Pluto

Question 10

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

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

Answer 10

of global climate effects initiated by dust and smoke that entered the atmosphere after the impact

Question 11

Each white dot in this figure represents the location of a small body in our solar system. The donut shaped ring of white dots represents the region of our solar system that we call:

the asteroid belt.
the Sun's rings.
the Oort cloud.
the Kuiper belt.

Answer 11

the asteroid belt.

Question 12

This graph shows the number of asteroids with different orbital periods. Notice the gap indicated by the black arrow. What does this graph tell us about this gap?

There are more asteroids concentrated at the orbital period indicated by the arrow than at any other orbital period.
Asteroids with an orbital period of about 4 years are all located very close together - so close that collisions occur frequently.
There are exactly 495 asteroids with an orbital period of 4 years.
There are few if any asteroids at the indicated orbital period of about 4 years.

Answer 12

There are few if any asteroids at the indicated orbital period of about 4 year

Question 13

This photo shows comet Hale Bopp over Mono Lake in California. Suppose you had taken another photograph from the same spot 10 minutes after this photo was taken. How would the scene have appeared at that time?

We'd still see the same stars, but the comet would be out of sight, having passed below the horizon.
It would have looked virtually the same.
We would see lots of steam coming from the point where the comet crashed into the lake.
We'd still see the same stars, but the comet would have moved far enough so that we'd be able to see only its tails and not its coma above the horizon.

Answer 13

It would have looked virtually the same.

Question 14

Each white dot in this figure represents the location of a small body in our solar system. The donut shaped ring of white dots just beyond Neptune’s orbit represents the part of our solar system that we call:

the Oort cloud.
the solar nebula.
the asteroid belt.
the Kuiper belt.

Answer 14

the Kuiper belt.

Question 15

This graph shows the frequency of impacts on Earth by objects of various sizes. According to this graph, objects smaller than about 1 meter in diameter hit Earth ________.

about once every 1 million years
never
every day
about once a year

Answer 15

every day

Question 16

This graph shows the frequency of impacts on Earth by objects of various sizes. According to this graph, objects large enough to cause a mass extinction hit Earth ________.

about once every 50 million years
about once in Earth's history
about once every 1,000 years
about once every 500 million years

Answer 16

about once every 50 million years

Question 17

Listed following are some distinguishing characteristics of comets, meteors, and asteroids. Match these to the appropriate category of objects. Comets:

Most are located either in kuiper belt or Oort cloud
Visible in the sky as a fuzzy patch of light that rises and sets with the stars
form a comma when near the sun
visible in the sky as a bright streak of light for only a few seconds
dust particles entering Eart’s atmosphere at high speed
typically orbit the sun at approximately 3 au
compositions similar to that of the terrestrial planets

Answer 17

Most are located either in kuiper belt or Oort cloud
Visible in the sky as a fuzzy patch of light that rises and sets with the stars
form a comma when near the sun

Question 18

Listed following are some distinguishing characteristics of comets, meteors, and asteroids. Match these to the appropriate category of objects. Meteors:

Most are located either in kuiper belt or Oort cloud
Visible in the sky as a fuzzy patch of light that rises and sets with the stars
form a comma when near the sun
visible in the sky as a bright streak of light for only a few seconds
dust particles entering Eart’s atmosphere at high speed
typically orbit the sun at approximately 3 au
compositions similar to that of the terrestrial planets

Answer 18

visible in the sky as a bright streak of light for only a few seconds
dust particles entering Eart’s atmosphere at high speed

Question 19

Listed following are some distinguishing characteristics of comets, meteors, and asteroids. Match these to the appropriate category of objects. Asteroids

Most are located either in kuiper belt or Oort cloud
Visible in the sky as a fuzzy patch of light that rises and sets with the stars
form a comma when near the sun
visible in the sky as a bright streak of light for only a few seconds
dust particles entering Eart’s atmosphere at high speed
typically orbit the sun at approximately 3 au
compositions similar to that of the terrestrial planets

Answer 19

typically orbit the sun at approximately 3 au

compositions similar to that of the terrestrial planets

Question 20

Listed following are several objects in the solar system. Rank these objects from left to right based on their distance from the Sun, from closest to farthest.
A typical asteroid in the asteroid belt, a trojan asteroid, a typical kuiper belt object, a typical oort cloud object

Answer 20

A typical asteroid in the asteroid belt,
a trojan asteroid,
a typical kuiper belt object,
a typical oort cloud object

Question 21

Listed following are several objects in the solar system. Rank these objects from left to right based on their orbital period around the Sun from shortest to longest.

Answer 21

A typical asteroid in the asteroid belt,
a trojan asteroid,
a typical kuiper belt object,
a typical oort cloud object

Question 22

Listed following are several objects in the solar system. Rank these objects from left to right based on the distance from the Sun at which they are presumed to have formed, from nearest to farthest.
a typical asteroid in the asteroid belt
a typical oort cloud object
a typical kuiper belt object

Answer 22

a typical asteroid in the asteroid belt
a typical oort cloud object
a typical kuiper belt object

Question 23

A comet entering the inner solar system from afar will __________.

form a tail and some time later form a coma.
form a coma and some time later form a tail
always form a tail, but only sometimes form a coma

Answer 23

form a coma and some time later form a tail

Question 24

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

heat from the Sun causes the comet’s nucleus to glow
increasing friction causes the comet’s nucleus to glow
sunlight reflects off the comet’s tail and coma
sunlight reflects off the comet’s nucleus

Answer 24

sunlight reflects off the comet’s tail and coma

Question 25

A comet’s plasma tail always points directly away from the Sun because __________.

of pressure exerted by the fast-moving charged particles in the solar wind
centrifugal forces throw the tail outward as the comet travels around the Sun
the comet’s nucleus overheats on the Sun-facing side, forcing energetic jets of gas to shoot out from the dark side
the tail is left behind as the comet moves through its orbit

Answer 25

of pressure exerted by the fast-moving charged particles in the solar wind

Question 26

About a trillion comets are thought to be located far, far beyond pluto in the

Answer 26

oort cloud

Question 27

The bright spherical part of a comet observed when it is close to the sun is the

Answer 27

coma

Question 28

A comet’s ________ stretches directly away from the sun.

Answer 28

plasma tail

Question 29

A comet’s _________ is the frozen portion of a comet

Answer 29

nucleus

Question 30

Particles ejected from a comet can cause a(n) _______ on earth

Answer 30

meteor shower

Question 31

The ______ extends from about beyond the orbit of Neptune to about twice the distance of Neptune from the Sun

Answer 31

Kuiper belt

Question 32

According to this graph, the minimum size of an object that could cause a mass extinction is a little less than _____.

	10 m
	100 m
	1 km
	10 km
	100 km

Answer 32

10 km

Question 33

According to the graph, an object 10 kilometers across hits Earth __________.

about once every 1 million years
about once every 100 million years
about once every 1 billion years
just once in Earth's history

Answer 33

about once every 100 million years

Question 34

What is the probability that an object 100 meters in diameter will hit Earth during the coming year?

	about 1 in 2
	about 1 in 10
	about 1 in 1000
	about 1 in 100 million
	zero

Answer 34

about 1 in 1000

Question 35

Based on this graph, which statement below most accurately describes the impacts we should expect on Earth during the coming year?

Earth will be hit by one object about 100 meters in diameter and several objects of about 10 meters in diameter.
Earth will be hit by one object that is a few meters in diameter, but no larger or smaller objects.
Only objects smaller than 1 meter across will hit Earth.
Earth will be hit by at least one object a few meters in diameter, along with many smaller objects.

Answer 35

Earth will be hit by at least one object a few meters in diameter, along with many smaller objects.

Question 36

The impact of a 100-meter object will not cause “widespread” devastation, but it could still kill millions of people if it struck a major city. In Part C, you found that the probability of such an impact in any single year is only 1 in 1000. Suppose we learn that it has already been 1200 years since the last such impact. What would that tell us?

There must be something wrong with the graph, because if the 1 in 1000 probability were correct, then there would have been an impact some time during the past 1000 years. Since there wasn't, the actual probability must be lower than 1 in 1000.
We are overdue for the impact of a 100-meter object, so we should expect the impact of an even larger object during the next few years.
We are clearly due for such an impact, so the actual probability for the coming year must be much higher than 1 in 1000.
Nothing; we would still presume that the chance of such an impact during the next year is 1 in 1000.

Answer 36

Nothing; we would still presume that the chance of such an impact during the next year is 1 in 1000.

Question 37

Which of the following statements best describes the size of the largest asteroid, Ceres?

It is no larger than a typical mountain on one of the terrestrial planets.
It is smaller than the jovian planets but larger than the terrestrial planets.
It is a little less than half the diameter of our Moon.
It is about the size of a terrestrial planet.

Answer 37

It is a little less than half the diameter of our Moon.

Question 38

If we could put all the asteroids together, their total mass would be ______.

much less than the mass of any terrestrial planet
about the mass of Mercury
greater than the mass of Earth but less than the mass of Jupiter
about the mass of Earth

Answer 38

much less than the mass of any terrestrial planet

Question 39

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

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

Answer 39

Gravitational tugs from Jupiter prevented material from collecting together to form a planet.

Question 40

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

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

Answer 40

the glow from a pea-size particle and the surrounding air as the particle burns up in our atmosphere

Question 41

In science fiction movies, spaceships are often shown dodging through large numbers of closely spaced, boulder-size objects. Which of the following real things in our solar system would look most like such science fiction dangers?

the atmosphere of Jupiter
the asteroid belt
the Oort cloud
the rings of Saturn

Answer 41

the rings of Saturn

Question 42

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

It would not have a coma.
It would have only one tail instead of two.
It would be much brighter in appearance.
It would not have a nucleus.

Answer 42

It would have only one tail instead of two.

Question 43

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?

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

Answer 43

It has been on its current orbit for only a very short time compared to the age of our solar system

Question 44

When we see a meteor shower, it means that _________.

Earth is crossing the orbit of a comet
an Earth-approaching asteroid has recently come very close to our planet
the solar wind is unusually strong
you should duck and run for cover to avoid being blasted on the head by a rock from space

Answer 44

Earth is crossing the orbit of a comet

Question 45

The discovery of Eris __________.

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

Answer 45

was not surprising, because other Kuiper belt objects approaching the size of Pluto had already been discovered

Question 46

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?

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

Answer 46

Fossilized dinosaur bones contain fragments of rock from the impact.