Deck 12: Planet Formation and Exoplanets

Question 1

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 when another solar system passed through ours.
C) Space debris is material that existed in our region of space before the Sun formed.
D) Space debris was formed when a planet crashed into the Sun.

Answer 1

Space debris is left over material from the early solar system that never formed into a planet.

Question 2

What kind of objects are located beyond the asteroid belt (3 AU from the Sun) and have extremely large masses with very low densities?

A) comets
B) asteroids
C) Terrestrial planets
D) Jovian planets

Answer 2

Jovian planets

Question 3

Which one of the following is a characteristic of Terrestrial planets?

A) high average density
B) orbits outside the asteroid belt
C) large diameters
D) many satellites

Answer 3

high average density

Question 4

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?

A) The planet will probably have about the same radius as Earth.
B) The planet will probably have a mean density of around 5 g/cm³.
C) The planet will probably have a composition that is mostly hydrogen and helium.
D) The planet will probably have liquid water oceans.

Question 5

Which of the following has a heavy element core and a very compressed liquid layer and atmosphere, both composed mostly of hydrogen?

A) Jupiter
B) Pluto
C) Venus
D) an asteroid

Question 6

Which one of the following objects is most like the planetesimals that formed in the solar nebula?

A) Vesta
B) Earth
C) Saturn
D) Venus

Question 7

Which of the following observed characteristics of the solar system is the solar nebula theory able to explain?

A) common direction of rotation of the planets
B) number of satellites of each planet
C) the formation of hydrogen atoms in the solar system from subatomic particles
D) number of planets of each type

Question 8

The planets all lie in nearly the same plane, resulting in a disk-like structure for the solar system. What is believed to be the reason for this disk-like structure?

A) The solar nebula from which the planets formed collapsed into a disk-like structure.
B) The bipolar flow from the young Sun cleared all material out of the nebula except the material 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.

Question 9

What is the collection of icy planetesimals in the region just beyond Neptune called?

A) Kuiper belt
B) asteroid belt
C) Oort cloud
D) planetesimal belt

Question 10

What observations of other stars have helped to validate the solar nebula theory?

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.

Question 11

Which one of the following is a characteristic of outer planets?

A) high average density
B) orbits inside the asteroid belt
C) large diameters
D) no satellites

Question 12

The asteroid belt is found between the orbits of two planets. What are they?

A) Earth and Mars
B) Mars and Jupiter
C) Jupiter and Saturn
D) Venus and Earth

Question 13

The hydrogen in our solar system was created from subatomic particles. Where did those particles come from?

A) our Sun
B) Jupiter
C) the big bang
D) supernovae

Question 14

Which one of the following is a characteristic of Jovian planets?

A) orbits inside the asteroids
B) low average density
C) craters in old surfaces
D) very few satellites

Question 15

Which statement about the difference between asteroids and comets is correct?

A) Asteroids originate from the Kuiper belt and comets originate from the Oort cloud.
B) Asteroids are much smaller than the nuclei of comets.
C) Asteroids are much older than comets.
D) Asteroids contain fewer volatiles than the nuclei of comets.

Question 16

Where are the satellites discovered by Galileo located?

A) They orbit the Terrestrial planets.
B) They orbit the planet Jupiter.
C) They orbit asteroids.
D) They orbit the planet Mars.

Question 17

The water molecules in your body contain hydrogen atoms. When did these hydrogen atoms form?

A) within a few minutes after the big bang
B) a few hundred million years after the big bang
C) about 5 billion years ago
D) less than 1 million years ago

Question 18

How do the Jovian planets compare to the Terrestrial planets?

A) They are more dense.
B) They have fewer moons.
C) They have much larger diameters.
D) They are much hotter.

Question 19

On a photograph of 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 12 km
B) about 120 km
C) about 350 km
D) about 1738 km

Question 20

Your blood contains iron atoms. Where did most of these iron atoms come from?

A) our Sun
B) Jupiter
C) the big bang
D) supernovae

Question 21

What is accretion?

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 removal of material from asteroids by the bombardment of the solar wind

Question 22

Approximately how old are the oldest rocks found on Earth?

A) 14 billion years old
B) 10.5 billion years old
C) 7.0 billion years old
D) 4.4 billion years old

Question 23

Which of the following is a solar system object that enters Earth's atmosphere, 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

Question 24

Which of the following shows materials in order of highest to lowest condensation temperature?

A) water ice, rock, iron
B) rock, iron, water ice
C) water ice, iron, rock
D) iron, rock, water ice

Question 25

Why was the Tagish Lake meteorite important?

A) Signs of life were discovered deep inside it.
B) It was the first meteorite recovered in Canada.
C) It was recovered only days after it fell to Earth.
D) Its large crater showed that cratering still occurs on Earth.

Question 26

Which of the following is a rock in space before it enters Earth's atmosphere?

A) meteoroid
B) meteorite
C) comet
D) meteor

Question 27

Which of the following best describes the origin of meteor showers?

A) asteroid
B) meteoroid
C) comet
D) Earth is crossing the orbit of a comet

Question 28

Which of the following is a solar system object that enters Earth's atmosphere and survives its passage through the atmosphere to reach the surface?

A) asteroid
B) meteor
C) meteorite
D) meteoroid

Question 29

The age of the solar system is estimated to be approximately 4.6 billion years based on which of the following types of data?

A) samples of proto-solar nebula
B) samples of the solar wind
C) crater counts on Earth
D) isotope ratios in meteorites

Question 30

Where in our solar system do we find the planets with the greatest uncompressed density?

A) the Jovian planets
B) the planets closest to the Sun
C) the planets farthest from the Sun
D) the planets with the largest mass

Question 31

After the first solid grains formed in our solar system, by what process were these particles then able to grow?

A) sublimation
B) accretion
C) hydration
D) condensation

Question 32

By what process did the first small solid grains or flakes form in our solar system?

A) accretion
B) sublimation
C) condensation
D) hydration

Question 33

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

Question 34

Why are meteorites important?

A) they can reveal the age of the solar system
B) they produce shooting stars
C) they can reveal the composition of Earth's rocks
D) they are unique, unusual rocks

Question 35

Which of the following best describes an iron meteorite?

A) has a dark, irregular surface and contains small, glassy spheres
B) heavy for its size and has smooth surface
C) heavy for its size and has dark, irregular surface
D) has a dark, irregular surface and crumbles easily

Question 36

How is the density different in different interior regions of a terrestrial planet?

A) the core has a higher density than the mantle
B) the core has a lower density than the mantle
C) there is no way to measure changes in interior density
D) there is no separation according to density

Question 37

How are radioactive materials 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.

Question 38

Which of the following is a streak of light produced by a small bit of matter from space burning up in Earth's atmosphere?

A) asteroid
B) meteoroid
C) comet
D) meteor

Question 39

The diagram 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) 2.6 billion years
B) 3.9 billion years
C) 5.2 billion years
D) 6.5 billion years

Question 40

Which of the following missions is NOT possible for a spacecraft to accomplish?

A) visit an object in the Kuiper belt
B) fly through the tail of a comet
C) orbit an asteroid
D) land on the surface of Jupiter

Question 41

How did protoplanets develop?

A) They grew in size primarily by accretion.
B) They grew in size primarily by condensation.
C) They grew in size by collecting the particles in the solar wind.
D) They grew in size by the collision and coalescing of planetesimals.

Question 42

How do debris disks and planet-forming disks differ?

A) Debris disks have higher density than planet-forming disks.
B) Debris disks contain larger amounts of gas than planet-forming disks.
C) Debris disks are found around older stars and planet-forming disks around younger stars.
D) Only debris disks are expected to be affected by the gravity of planets within them.

Question 43

What is the term for the separation of material in a newly formed planet or asteroid according to density?

A) precipitation
B) sublimation
C) condensation
D) differentiation

Question 44

What could have caused the proto-Jovian planets to grow very hot?

A) the in-falling of material at high velocity
B) radioactivity of light elements such as hydrogen and helium
C) heat from the Sun
D) collisions with large planetesimals

Question 45

Mercury has a mass of 3.3 × 10²³ kg and a radius of 2439 km. 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?

A) about 67 particles per second
B) about 100 million particles per second
C) about 100 billion particles per second
D) about 3.3 × 10²¹ particles per second

Question 46

What is an extrasolar planet?

A) a planet that orbits our Sun that we have not yet discovered
B) a planet found orbiting around a star other than the Sun
C) a planet just outside the edge of the solar system
D) a planet just outside the surface of our Sun

Question 47

According to the condensation sequence, what 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

Question 48

The Terrestrial planets are thought to have formed by accreting solid planetesimals, all with about the same composition. What does this mean?

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 and then differentiated into a high-density iron metal core and low-density silicate crust.
D) They were initially collections of solid particles, which melted and then differentiated into a high-density silicate core and low-density iron metal crust.

Question 49

Approximately how many exoplanets had been confirmed as of 2019?

A) about 4000
B) about 3000
C) about 300
D) about 40

Question 50

How do we know that Jovian planets formed within about 10 million years of the formation of the solar nebula?

A) It takes about 10 million years for gas giants to grow by gravitational collapse.
B) After 10 million years there was very little gas present in the solar nebula.
C) We have estimated their ages using the proportions of radioactive elements in their atmospheres.
D) We have estimated their ages by measuring how much heat is left over from their formation.

Question 51

Which assumption must be true for the condensation sequence to explain the compositions of planets found in our solar system?

A) The planets must have formed close to where they are found today.
B) The Sun must have been cooler when it first formed than it is today.
C) The planets must have formed within about 30 million years.
D) The temperature of the entire solar nebula must have reached 1500 K.

Question 52

What are the characteristics of most of the extrasolar planets discovered so far?

A) larger than Earth and orbit very close to the star
B) much smaller than Earth and orbit very far from the star
C) small and rocky and orbit very far from the star
D) smaller than Earth and orbit close to the star

Question 53

Which of the following correctly matches the type of grain with the location where it condensed from the solar nebula?

A) icy grains, beyond the present orbit of Jupiter
B) metallic grains, near the present orbit of Earth
C) icy grains, near the present orbit of Mercury
D) metallic grains, beyond the present orbit of Jupiter

Question 54

Which of the following is believed to form part of the current atmosphere of Earth?

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 vapourizing of the glaciers from the last ice age
C) gases that were outgassed from the heated rocks sometime after the planet formed
D) hydrogen and helium from a collision between the Sun and another star

Question 55

What is outgassing?

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 gases from a planet's interior
D) the removal of hydrogen via nuclear fusion

Question 56

What is the term used to describe the phenomenon that involves sudden, sometimes violent events?

A) gravitational collapse
B) heavy bombardment
C) evolutionary theory
D) catastrophic theory

Question 57

What is one cause of a newly formed planet or large asteroid becoming molten?

A) sublimation
B) decay of radioactive element isotopes
C) differentiation
D) ignition of hydrogen fusion

Question 58

Why is 51 Pegasi so important?

A) because it is a pulsar with planets orbiting around it
B) because it is a star with a planet that is known to support intelligent life
C) because it is the largest satellite of Jupiter and is suspected to have liquid oceans
D) because it is the first star similar to our Sun that was found to have a planet orbiting it

Question 59

Why would the larger planetesimals have grown faster than the smaller planetesimals?

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.

Question 60

What pushed gas and dust particles out of the solar nebula?

A) the solar wind
B) outgassing
C) the Sun's magnetic field
D) differentiation

Question 61

The description "large somewhat dirty snowball" best describes a ____________________.

Question 62

In which way is the TRAPPIST-1 system similar to our own solar system?

A) Its habitable zone contains more than one planet.
B) Its star is very similar to our Sun.
C) Its planets are tidally locked to their star.
D) Its planets are all about the same size.

Question 63

What is the main reason why it is so hard to directly image exoplanets?

A) Exoplanets are typically very far from Earth.
B) Exoplanets are typically much smaller than their parent stars.
C) Exoplanets are typically much dimmer than their parent stars.
D) Exoplanets are typically very far from their parent star.

Question 64

Small, glassy spheres found in chondrites are called ____________________.

Question 65

Which property of an exoplanet can be determined if it is detected using the transit method?

A) size
B) mass
C) temperature
D) age

Question 66

A certain Earth-sized exoplanet is said to be in the habitable zone. What can we conclude about the exoplanet?

A) The planet is likely inhabited with some form of life.
B) The temperature may be right for liquid water to exist on its surface.
C) A certain region of the planet has the conditions required to sustain human life.
D) The planet's atmosphere has a similar composition to Earth's atmosphere.

Question 67

Which of the following exoplanets would be easiest to detect using the transit method?

A) an Earth-sized planet orbiting close to its parent star, viewed "edge-on"
B) a Neptune-sized planet orbiting close to its parent star, viewed "edge-on"
C) a Saturn-sized planet orbiting far from its parent star, viewed "face-on"
D) a Jupiter-sized planet orbiting far from its parent star, viewed "face-on"

Question 68

Why were many of the first planets found using the Doppler method "hot Jupiters"?

A) Young Jupiter-mass planets are easier to see when they orbit far from their parent star.
B) Larger planets block more light when they pass in front of their parent star.
C) Massive planets with small orbits have a stronger gravitational effect on their parent star.
D) Planets with higher temperatures cause larger shifts in the spectra of their stars.

Question 69

The collection of icy planetesimals orbiting in a region just beyond Neptune is called the ____________________ belt.

Question 70

Which property of an exoplanet influences the amount of Doppler shift that it induces in the spectra of its parent star?

A) its size
B) its mass
C) the composition of its atmosphere
D) its age

Question 71

Which discovery about exoplanetary systems was most surprising considering how our own solar system formed?

A) Some exoplanetary systems contain planets within their habitable zones.
B) Some exoplanetary systems contain planets with a wide range of densities.
C) Some exoplanetary systems contain more than one Earth-sized planets.
D) Some exoplanetary systems contain Jupiter-sized planets that orbit close to their stars.

Question 72

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

Question 73

Which of the following exoplanets would be easiest to detect using the Doppler method?

A) a Jupiter-mass planet orbiting very far from its parent star
B) an Earth-mass planet orbiting very close to its parent star
C) a Jupiter-mass planet orbiting very close to its parent star
D) an Earth-mass planet orbiting very far from its parent star

Question 74

If our Sun were replaced by a much hotter and brighter star, what would happen to the position of the habitable zone in our solar system?

A) It would move inwards, closer to the star.
B) It would stay in its current position.
C) It would move outwards, away from the star.
D) We need to know the size of the star to determine this.

Question 75

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

Question 76

What type of planet was common among the first planets found using the Doppler method?

A) Earth-like planets
B) super-Earths
C) hot Jupiters
D) mini-Neptunes

Question 77

Why was the Kepler space telescope focused on a single patch of sky for many years?

A) It was studying planets around a particular star in that patch of sky.
B) It was trying to detect planets that repeatedly pass in front of their star.
C) It was trying to detect which stars in that patch of sky move due to an unseen planet.
D) One of its steering mechanism was broken, preventing it from pointing in other directions.

Question 78

Approximately how many Earth-sized planets are believed to exist in the Milky Way Galaxy?

A) a few dozen
B) several thousand
C) several million
D) several billion

Question 79

Which exoplanet detection method has found the greatest number of exoplanets?

A) direct imaging
B) the transit method
C) the Doppler method
D) adaptive optics

Question 80

The ____________________ planets have larger radii than the ____________________ planets.