Quiz #3 Review

Question 1

Which of the following properties of terrestrial
planets is unique to Earth?
A. Liquid water
B. A rocky mantle and iron core
C. History of volcanism
D. A large moon

Answer 1

D - a large moon

Question 2

Which planets are the terrestrial planets?

Answer 2

Mercury, Venus, Earth, Mars

Question 3

Which planets are the gas giants?

Answer 3

Saturn and Jupiter

Question 4

Which planets are the ice giants?

Answer 4

Uranus and Neptune

Question 5

Which is NOT a common property of the gas and ice
giants?
A. Multiple icy moons
B. A history of volcanism
C. Thick gas envelopes
D. Rings

Answer 5

B - a history of volcanism

Question 6

Which criterion for
being a “planet” does Pluto fail?
A. …is orbiting the sun
B. …is massive enough for its own gravity
to pull it into a spherical shape (without
igniting stellar fusion)
C. …has cleared smaller objects from the
neighborhood of its orbit

Answer 6

C - Pluto has not cleared smaller objects from the neighborhood of its orbit.

Question 7

Where are Kuiper Belt objects located?
A. in orbit around Mars
B. in orbit just beyond the asteroid belt
C. beyond Neptune’s orbit
D. within a vast spherical region called the Oort Cloud

Answer 7

C - beyond Neptune’s orbit

Question 8

Most asteroids are found
A. between the Sun and the orbit of Mars.
B. in the asteroid belt.
C. in the Kuiper Belt.
D. in the Oort Cloud

Answer 8

B - in the asteroid belt

Question 9

Comets differ from asteroids in that…
A. They have significant amounts of ice
B. They have two tails
C. They have eccentric orbits
D. All of the above

Answer 9

D - All of the above!

Question 10

Which bodies of the solar system contain the least ice and water?
A. Terrestrial planets
B. Galilean moons
C. Ice giants
D. Comets

Answer 10

A - Terrestrial planets contain the least ice and water.

Question 11

How did humanity first measure the distance between
Earth and the sun?
A. By measuring the changing lengths of the shadows as
Earth orbits the sun
B. By measuring the parallax of the transit of Venus
C. By reflecting light off the moon
D. By sending a probe to the sun

Answer 11

B - By measuring the parallax of the transit of Venus.

Question 12

Why do the planets line up along the ecliptic?
A. These photographs are pure coincidence
B. They are very far away from Earth and so appear to
be in a straight line
C. Their orbits trace the flat disk in which they formed

Answer 12

C - Planets line up along the ecliptic because their orbits trace the flat disk in which they are formed.

Question 13

What is the core accretion model for planet-forming?

Answer 13

• combination of elements
• rocky core forms
• gas accretes on the core
• the gas giant is complete

Question 14

What is the gas instability model for planet-forming?

Answer 14

• gas revolves around a star
• some gas collapses over time due to gravity
• giant planet forms quickly before a core could form

Question 15

Which type of evidence could distinguish the “core
accretion” model from the “gas instability” model of giant planet formation?
A. The existence of gas giant planets around other stars
B. The existence of a rocky core in Jupiter and Saturn
C. The existence of helium in the atmospheres of gas
giants

Answer 15

B - The existence of a rocky core in Jupiter and Saturn.

Question 16

The gas instability model explains the structure of the
terrestrial planets.
A. True
B. False

Answer 16

B - False!

Question 17

According to the core accretion hypothesis, the asteroids in the asteroid belt are the remains of a planet that broke apart after it was fully formed.
A. true
B. false

Answer 17

B - False: Asteroids are actually the remains of a planet that NEVER FORMED IN THE FIRST PLACE.

Question 18

What role does Jupiter play in the formation of the solar system?
A. Affects the sizes of the terrestrial planets
B. Affects the orbits of water-bearing small solar system
bodies (comets and Kuiper Belt Objects)
C. Affects the orbits of the other giant planets
D. All of the above

Answer 18

D - All of the above!

Question 19

How did Earth get its water?
A. From comets (or
other small icy
bodies) steered by
Jupiter
B. Earth formed with
more water than the
other terrestrial
planets

Answer 19

We don’t necessarily know!!

Question 20

Why don’t astronomers know where all the Earth-
crossing asteroids are located?
A. Their orbits are highly elliptical.
B. They reflect too much sunlight.
C. Most of them are hidden between the rings of Jupiter and Saturn.
D. They are small, faint, and reflect only a small amount of sunlight.

Answer 20

D - The Earth-crossing asteroids are small, faint and don’t reflect a lot of sunlight.

Question 21

Based on the orbit of 2017/U1, astronomers concluded that it is a(n)
A. Comet
B. Near-Earth Asteroid
C. Object from outside the solar system
D. Alien spaceship

Answer 21

C - outside the solar system!

Question 22

Which fundamental law best explains why the star (in addition to the planet) orbits the center of mass?
A. Orbits sweep equal areas in equal times.
B. The orbital period squared is proportional to the semi-major axis cubed.
C. An object in motion stays in motion; an object at rest.
D. For every action there is an equal and opposite reaction.

Answer 22

D - Newton’s third law

Question 23

The wavelength is related to which
property of the planet?
A. Its mass
B. Its size
C. Its orbital period
D. Its eccentricity

Answer 23

C - orbital period

Question 24

The amplitude is related to which
property of the planet?
A. Its mass
B. Its size
C. Its orbital period
D. Its eccentricity

Answer 24

A - the mass

Question 25

The change in brightness of the star during a transit is proportional to... A. The planet diameter B. The planet diameter squared C. The planet diameter cubed D. The planet orbital distance

Answer 25

B - the planet diameter squared

Question 26

The time between transits is equal to... A. Half of an Earth-year B. One rotation of the exoplanet on its axis (a “day”) C. One month of the exoplanet D. One orbital period of the exoplanet (a “year”)

Answer 26

D - a "year" for the exoplanet

Question 27

The transits of a planet look better from space than from the ground in part because there is no atmospheric turbulence in space. A. True B. False

Answer 27

A - true

Question 28

Which transiting planets are hardest to find? A. Small planets close to their stars B. Small planets far from their stars C. Big planets close to their stars D. Big planets far from their stars

Answer 28

B - small planets far from their stars

Question 29

What is one advantage of the microlensing technique for discovering exoplanets? A. It is very sensitive to Earth-like planets. B. It is possible to re-observe the planets we discover to search for liquid water. C. It is very effective at discovering planets around the stars closest to the sun. D. The observations can be done quickly.

Answer 29

A - Microlensing is very sensitive to Earth-like planets.

Question 30

Which of the following statements best describes our understanding about how common Earth-like planets are? A. Because most Earth-like planets do not transit their stars, we have no way of gathering statistical information about them. B. Because Earth-like planets make a very shallow transit depth, we have no way of gathering statistical information about them. C. Because we understand geometry and our detection capabilities, we can use statistics to infer the number of Earth-like planets in the galaxy. D. Our best estimate of the number of Earth-like planets in the galaxy is the number of Earth-like planets we have detected.

Answer 30

C!

Question 31

Which of the following statements best describes our understanding about rocky exoplanets? A. All exoplanets smaller than 1.5 times the diameter of Earth are rocky. B. All exoplanets larger than 1.5 times the diameter of Earth have thick gas envelopes. C. Rocky exoplanets are generally smaller than 1.5 times the diameter of Earth. D. We have no way of predicting whether an exoplanet will be rocky from its size alone.

Answer 31

C - Exoplanets are generally smaller than 1.5 times the diameter of Earth.

Question 32

Exoplanets are fundamentally different from the solar system planets, so our theories of planet formation do not need to explain them. A. True B. False

Answer 32

B - False!

Question 33

Which of the following statements best describes our understanding of whether or not there are patterns in planetary systems? A. The types of planets orbiting a star are random. B. The types of planets orbiting a star originally had patterns, but the patterns got randomized. C. The types of planets orbiting a star originally had patterns, and in many systems those patterns are still visible today. D. We have not discovered enough exoplanets to determine whether their planetary systems have patterns or not.

Answer 33

C - The original systems had patterns, and we can still see some in place today.