Question 1

What evidence do we have that the accretion disk that formed the Solar System was initially very centrally condensed?

Accepted Answer

The Sun contains 99 percent of all the mass of the Solar System.

Question 2

In protoplanetary environments,the plane of an accretion disk is perpendicular to the axis of rotation of the interstellar cloud out of which it forms.

Accepted Answer

A) True 
 B)False  True

Question 3

The fact that Jupiter's radius is contracting at a rate of 1 mm per year results in:

Accepted Answer

A) Jupiter's rotation rate slowing down with time 
B) Jupiter's shape being noticeably oblate 
C) Jupiter moving slightly farther from the Sun with time 
D) Jupiter radiating more heat than it receives from the Sun 
E) Jupiter having a strong magnetic field 
A) Jupiter's rotation rate slowing down with time 
B) Jupiter's shape being noticeably oblate 
C) Jupiter moving slightly farther from the Sun with time 
D) Jupiter radiating more heat than it receives from the Sun 
E) Jupiter having a strong magnetic field D

Question 4

Compare the orbital angular momentum of the Earth and Jupiter.Which is larger and by how much? (Note that Jupiter's mass is 318 times that of the Earth;the semimajor axis of Jupiter's orbit is 5.2 AU;and Jupiter's orbital period is 12 years. )

Accepted Answer

The orbital angular momentum is equal to

Question 5

If an interstellar cloud having a diameter of 1016 m and a rotation period of a million years were to collapse to form a sphere that had the diameter of our Solar System,approximately 40 AU,what would its rotation period be? Assume the cloud's total mass and angular momentum did not change.

Accepted Answer

A) 1 million years 
B) 600 years 
C) 1 year 
D) 6 years 
E) 4 months 
A) 1 million years 
B) 600 years 
C) 1 year 
D) 6 years 
E) 4 months

Question 6

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 7

Comets and asteroids are:

Accepted Answer

A) other names for moons of the planets 
B) primarily located within 1 AU of the Sun 
C) all more massive than Earth's Moon 
D) material left over from the formation of the planets 
E) other names for meteors 
A) other names for moons of the planets 
B) primarily located within 1 AU of the Sun 
C) all more massive than Earth's Moon 
D) material left over from the formation of the planets 
E) other names for meteors

Question 8

The maximum mass of a planet is approximately 0.08 times the mass of the Sun.

Accepted Answer

A) True 
 B)False

Question 9

Earth-sized planets have been found using the _________ method(s).

Accepted Answer

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

Question 10

Why do the outer giant planets have massive gaseous atmospheres of hydrogen and helium while 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 gravitationally hold on to these gases before the solar wind dispersed the accretion disk. 
C) The inner planets were too close to the Sun,and the solar wind blew away their original gaseous atmospheres. 
D) Frequent early collisions by comets with the inner planets caused most of their original atmospheres to dissipate. 
E) Temperatures were too high in the region of the Solar System that contains the inner planets. 
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 gravitationally hold on to these gases before the solar wind dispersed the accretion disk. 
C) The inner planets were too close to the Sun,and the solar wind blew away their original gaseous atmospheres. 
D) Frequent early collisions by comets with the inner planets caused most of their original atmospheres to dissipate. 
E) Temperatures were too high in the region of the Solar System that contains the inner planets.

Question 11

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 12

What is the difference between refractory and volatile materials?

Accepted Answer

Refractory materials are capab

Question 13

How do astronomers explain the basic difference in composition between the inner planets and the outer planets?

Accepted Answer

The inner planets (Mercury,Venus,Earth,a

Question 14

Astronomers have used radial velocity monitoring to discover:

Accepted Answer

A) extrasolar planetary systems that are similar to our own solar system 
B) Earth-sized planets around other stars 
C) Earth-sized planets at distances of 10 AU from their parent stars 
D) extrasolar planetary systems that contain more than one planet 
E) all of the above 
A) extrasolar planetary systems that are similar to our own solar system 
B) Earth-sized planets around other stars 
C) Earth-sized planets at distances of 10 AU from their parent stars 
D) extrasolar planetary systems that contain more than one planet 
E) all of the above

Question 15

Explain why an accretion disk forms around a protostar when an interstellar cloud collapses.

Accepted Answer

As the cloud collapses,the rat

Question 16

Approximately how much mass was there in the protoplanetary disk out of which the planets formed,compared to the mass of the Sun?

Accepted Answer

A) 50 percent 
B) 25 percent 
C) 10 percent 
D) 5 percent 
E) < 1 percent 
A) 50 percent 
B) 25 percent 
C) 10 percent 
D) 5 percent 
E) < 1 percent

Question 17

What prevented the Moon from maintaining any atmosphere with which it originally formed?

Accepted Answer

A) It repeatedly collided with planetesimals. 
B) It is too close to the Sun. 
C) The solar wind blew it away. 
D) It is not massive enough. 
E) It is tidally locked to Earth. 
A) It repeatedly collided with planetesimals. 
B) It is too close to the Sun. 
C) The solar wind blew it away. 
D) It is not massive enough. 
E) It is tidally locked to Earth.

Question 18

Astronomers believe that Venus initially formed with the thick atmosphere,primarily made of carbon dioxide,which it currently has.

Accepted Answer

A) True 
 B)False

Question 19

If an astronomer on a planet orbiting a nearby star observed the Sun when Neptune was transiting in front of the Sun,how would the Sun's brightness change? Note that the radius of Neptune is 2.5 × 107 m.

Accepted Answer

A) The Sun's brightness would decrease by 0.1 percent. 
B) The Sun's brightness would increase by 0.1 percent. 
C) The Sun's brightness would increase by 1 percent. 
D) The Sun's brightness would decrease by 1 percent. 
E) The Sun's brightness would not change at all. 
A) The Sun's brightness would decrease by 0.1 percent. 
B) The Sun's brightness would increase by 0.1 percent. 
C) The Sun's brightness would increase by 1 percent. 
D) The Sun's brightness would decrease by 1 percent. 
E) The Sun's brightness would not change at all.

Question 20

Our Solar System is the only planetary system in our galaxy.

Accepted Answer

A) True 
 B)False

Exam 7: The Birth and Evolution of Planetary Systems

What evidence do we have that the accretion disk that formed the Solar System was initially very centrally condensed?

In protoplanetary environments,the plane of an accretion disk is perpendicular to the axis of rotation of the interstellar cloud out of which it forms.

The fact that Jupiter's radius is contracting at a rate of 1 mm per year results in:

Compare the orbital angular momentum of the Earth and Jupiter.Which is larger and by how much? (Note that Jupiter's mass is 318 times that of the Earth;the semimajor axis of Jupiter's orbit is 5.2 AU;and Jupiter's orbital period is 12 years. )

If an interstellar cloud having a diameter of 1016 m and a rotation period of a million years were to collapse to form a sphere that had the diameter of our Solar System,approximately 40 AU,what would its rotation period be? Assume the cloud's total mass and angular momentum did not change.

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

Comets and asteroids are:

The maximum mass of a planet is approximately 0.08 times the mass of the Sun.

Earth-sized planets have been found using the _________ method(s).

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

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 do astronomers explain the basic difference in composition between the inner planets and the outer planets?

Astronomers have used radial velocity monitoring to discover:

Explain why an accretion disk forms around a protostar when an interstellar cloud collapses.

Approximately how much mass was there in the protoplanetary disk out of which the planets formed,compared to the mass of the Sun?

What prevented the Moon from maintaining any atmosphere with which it originally formed?

Astronomers believe that Venus initially formed with the thick atmosphere,primarily made of carbon dioxide,which it currently has.

If an astronomer on a planet orbiting a nearby star observed the Sun when Neptune was transiting in front of the Sun,how would the Sun's brightness change? Note that the radius of Neptune is 2.5 × 107 m.

Our Solar System is the only planetary system in our galaxy.

Why Learn Astronomy

Patterns in the Skymotions of Earth

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 Liquid the Giant Planets

Planetary Adornments Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

The Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters

If an interstellar cloud having a diameter of 10¹⁶ m and a rotation period of a million years were to collapse to form a sphere that had the diameter of our Solar System,approximately 40 AU,what would its rotation period be? Assume the cloud's total mass and angular momentum did not change.

If an astronomer on a planet orbiting a nearby star observed the Sun when Neptune was transiting in front of the Sun,how would the Sun's brightness change? Note that the radius of Neptune is 2.5 × 10⁷ m.