Question 1

Why might a newly discovered comet contain clues to the composition of the early solar nebula?

Accepted Answer

Comets are believed to be made of ice an

Question 2

What does conservation of angular momentum mean?

Accepted Answer

It means the angular momentum

Question 3

What do astrobiologists on the Kepler Mission look for when searching for potentially habitable planets around other stars?

Accepted Answer

They look for Earth-sized planets orbiti

Question 4

Astronomers believe that the "hot Jupiters" found orbiting other stars must have migrated inward over time

Accepted Answer

A)  by slowly accreting large amounts of gas and increasing their gravitational pull. 
B)  by losing their gas because of evaporation. 
C)  by losing orbital angular momentum. 
D)  after colliding with another planet. 
E)  after a close encounter between their star and another star. 
A)  by slowly accreting large amounts of gas and increasing their gravitational pull. 
B)  by losing their gas because of evaporation. 
C)  by losing orbital angular momentum. 
D)  after colliding with another planet. 
E)  after a close encounter between their star and another star.

Question 5

What happens to the kinetic energy of gas as it falls toward and eventually hits the accretion disk surrounding a protostar?

Accepted Answer

A)  It is immediately converted into photons, giving off a flash of light on impact. 
B)  It is converted into thermal energy, heating the disk. 
C)  It is converted into potential energy as the gas plows through the disk and comes out the other side. 
D)  It becomes the kinetic energy of the orbit of the gas in the accretion disk around the protostar. 
E)  It disappears into interstellar space. 
A)  It is immediately converted into photons, giving off a flash of light on impact. 
B)  It is converted into thermal energy, heating the disk. 
C)  It is converted into potential energy as the gas plows through the disk and comes out the other side. 
D)  It becomes the kinetic energy of the orbit of the gas in the accretion disk around the protostar. 
E)  It disappears into interstellar space.

Question 6

Why do the outer giant planets have massive gaseous atmospheres of hydrogen and helium whereas the inner planets do not?

Accepted Answer

A)  These gases were more abundant in the outer regions of the accretion disk where the outer planets formed. 
B)  The outer planets grew massive quickly enough to hold on to these gases through gravity before the solar wind dispersed the accretion disk. 
C)  The inner planets "used up" all of the rocky materials. 
D)  Frequent early collisions by comets with the inner planets caused most of their original atmospheres to dissipate. 
E)  They were most likely captured by the Sun after our Solar System formed. 
A)  These gases were more abundant in the outer regions of the accretion disk where the outer planets formed. 
B)  The outer planets grew massive quickly enough to hold on to these gases through gravity before the solar wind dispersed the accretion disk. 
C)  The inner planets "used up" all of the rocky materials. 
D)  Frequent early collisions by comets with the inner planets caused most of their original atmospheres to dissipate. 
E)  They were most likely captured by the Sun after our Solar System formed.

Question 7

What is a protostar?

Accepted Answer

A)  a planet like Jupiter 
B)  a hot star 
C)  a large ball of gas not yet hot enough at its core to be a star 
D)  a large ball of gas too hot at its core to be a star 
E)  a star with too much angular momentum 
A)  a planet like Jupiter 
B)  a hot star 
C)  a large ball of gas not yet hot enough at its core to be a star 
D)  a large ball of gas too hot at its core to be a star 
E)  a star with too much angular momentum

Question 8

Which method can be used to determine the radius of an extrasolar planet?

Accepted Answer

A)  Doppler shift 
B)  transit 
C)  microlensing 
D)  direct imaging 
E)  none of these 
A)  Doppler shift 
B)  transit 
C)  microlensing 
D)  direct imaging 
E)  none of these

Question 9

We expect a planet that forms close to its star to be

Accepted Answer

A)  rocky in composition like terrestrial planets. 
B)  a comet or asteroid. 
C)  rich in volatile ices. 
D)  composed primarily of hydrogen and helium. 
E)  similar in mass to Earth. 
A)  rocky in composition like terrestrial planets. 
B)  a comet or asteroid. 
C)  rich in volatile ices. 
D)  composed primarily of hydrogen and helium. 
E)  similar in mass to Earth.

Question 10

The smallest grains of dust stick together in an accretion disk by which force?

Accepted Answer

A)  gravitational force 
B)  electrostatic force 
C)  magnetic force 
D)  quantum mechanical force 
E)  strong force 
A)  gravitational force 
B)  electrostatic force 
C)  magnetic force 
D)  quantum mechanical force 
E)  strong force

Question 11

What is the ratio of the orbital angular momentum of Earth compared to its spin angular momentum? Note that Earth has a radius of 6 * 106 m, and 1 AU is 1.5 *1011 m.

Accepted Answer

A)  1 
B)  70 
C)  640 
D)  25,000 
E)  4.3* 106 
A)  1 
B)  70 
C)  640 
D)  25,000 
E)  4.3* 106

Question 12

Explain why astronomers believe that the formation of planets is a natural by-product of star formation.

Accepted Answer

To explain the structure of the solar sy

Question 13

What is the difference between refractory and volatile materials?

Accepted Answer

Refractory materials are capab

Question 14

How many exoplanets are known (that is, have been confirmed) to exist?

Accepted Answer

A)  8 
B)  9 
C)  150 
D)  1,000-2,000 
E)  more than 3,000 
A)  8 
B)  9 
C)  150 
D)  1,000-2,000 
E)  more than 3,000

Question 15

If you are spinning in a chair and then you spread your arms out wide, you should expect

Accepted Answer

A)  your rotation rate to slow. 
B)  your rotation rate to increase. 
C)  to heat up. 
D)  to cool down. 
E)  none of these 
A)  your rotation rate to slow. 
B)  your rotation rate to increase. 
C)  to heat up. 
D)  to cool down. 
E)  none of these

Question 16

Which of the following is a giant planet?

Accepted Answer

A)  Mercury 
B)  Jupiter 
C)  Venus 
D)  Earth 
E)  Pluto 
A)  Mercury 
B)  Jupiter 
C)  Venus 
D)  Earth 
E)  Pluto

Question 17

The Kepler Mission is designed to search for extrasolar planets using the ________ method.

Accepted Answer

A)  Doppler shift 
B)  transit 
C)  microlensing 
D)  direct imaging 
E)  radial velocity 
A)  Doppler shift 
B)  transit 
C)  microlensing 
D)  direct imaging 
E)  radial velocity

Question 18

Why does an accretion disk heat up?

Accepted Answer

As material falls onto the dis

Question 19

Because energy must be conserved, a collapsing cloud of gas must

Accepted Answer

A)  eventually expand again. 
B)  rotate more slowly with time. 
C)  always be at the same temperature. 
D)  heat up. 
E)  cool down. 
A)  eventually expand again. 
B)  rotate more slowly with time. 
C)  always be at the same temperature. 
D)  heat up. 
E)  cool down.

Question 20

Why do the terrestrial planets have a much higher fraction of their mass in heavy chemical elements than the giant planets?

Accepted Answer

A)  Terrestrial planets are low in mass and high in temperature, thus their lighter chemical elements eventually escaped to the outer reaches of the Solar System. 
B)  The heavier elements in the forming solar nebula sank to the center of the Solar System, thus the inner terrestrial planets formed mostly from heavy chemical elements. 
C)  The giant planets were more massive than terrestrial planets, and the giant planets preferentially pulled the lighter elements from the inner to the outer Solar System. 
D)  Terrestrial planets formed much earlier than giant planets, before the hydrogen and helium had a chance to cool and condense onto them. 
E)  Terrestrial planets are colder and thus more massive chemical elements condensed on them than on the giant planets. 
A)  Terrestrial planets are low in mass and high in temperature, thus their lighter chemical elements eventually escaped to the outer reaches of the Solar System. 
B)  The heavier elements in the forming solar nebula sank to the center of the Solar System, thus the inner terrestrial planets formed mostly from heavy chemical elements. 
C)  The giant planets were more massive than terrestrial planets, and the giant planets preferentially pulled the lighter elements from the inner to the outer Solar System. 
D)  Terrestrial planets formed much earlier than giant planets, before the hydrogen and helium had a chance to cool and condense onto them. 
E)  Terrestrial planets are colder and thus more massive chemical elements condensed on them than on the giant planets.

Exam 7: The Formation of Planetary Systems

Why might a newly discovered comet contain clues to the composition of the early solar nebula?

What does conservation of angular momentum mean?

What do astrobiologists on the Kepler Mission look for when searching for potentially habitable planets around other stars?

Astronomers believe that the "hot Jupiters" found orbiting other stars must have migrated inward over time

What happens to the kinetic energy of gas as it falls toward and eventually hits the accretion disk surrounding a protostar?

Why do the outer giant planets have massive gaseous atmospheres of hydrogen and helium whereas the inner planets do not?

What is a protostar?

Which method can be used to determine the radius of an extrasolar planet?

We expect a planet that forms close to its star to be

The smallest grains of dust stick together in an accretion disk by which force?

What is the ratio of the orbital angular momentum of Earth compared to its spin angular momentum? Note that Earth has a radius of 6 * 106 m, and 1 AU is 1.5 *1011 m.

Explain why astronomers believe that the formation of planets is a natural by-product of star formation.

What is the difference between refractory and volatile materials?

How many exoplanets are known (that is, have been confirmed) to exist?

If you are spinning in a chair and then you spread your arms out wide, you should expect

Which of the following is a giant planet?

The Kepler Mission is designed to search for extrasolar planets using the ________ method.

Why does an accretion disk heat up?

Because energy must be conserved, a collapsing cloud of gas must

Why do the terrestrial planets have a much higher fraction of their mass in heavy chemical elements than the giant planets?

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Planetary Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

The Interstellar Medium and Star Formation

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

Galaxies

The Milky Waya Normal Spiral Galaxy

The Expanding Universe

Cosmology

Large-Scale Structure in the Universe

Life

Filters

What is the ratio of the orbital angular momentum of Earth compared to its spin angular momentum? Note that Earth has a radius of 6 * 10⁶ m, and 1 AU is 1.5 *10¹¹ m.