Question 1

About what percentage of the mass of a molecular cloud is in the form of dust?

Accepted Answer

A) 10% 
B) 1% 
C) 50% 
D) 98% 
A) 10% 
B) 1% 
C) 50% 
D) 98%

Question 2

What produces the striking red, blue, and black colors of ionization nebulae?

Accepted Answer

The bright red color is produced by an e

Question 3

How do we learn about the conditions at the center of our own galaxy, the Milky Way?

Accepted Answer

A) We must look at the centers of other (external)galaxies and assume that they are similar to the Milky Way. 
B) High- resolution photographs obtained by the Hubble Space Telescope have revealed the galactic center using visible light. 
C) While we cannot see the galactic center with visible or ultraviolet light, radio and X- rays from the center can be detected and used to determine the conditions there. 
D) The gas and dust in the Milky Way prevent any type of direct observation of the galactic center, but theoretical models allow us to predict what is happening there. 
A) We must look at the centers of other (external)galaxies and assume that they are similar to the Milky Way. 
B) High- resolution photographs obtained by the Hubble Space Telescope have revealed the galactic center using visible light. 
C) While we cannot see the galactic center with visible or ultraviolet light, radio and X- rays from the center can be detected and used to determine the conditions there. 
D) The gas and dust in the Milky Way prevent any type of direct observation of the galactic center, but theoretical models allow us to predict what is happening there.

Question 4

What do we mean by the interstellar medium?

Accepted Answer

A) the gas and dust that lie in between the stars in the Milky Way galaxy 
B) the middle section of the Milky Way galaxy 
C) the name of an oracle who can channel messages from beings that live near the star called Vega 
D) the dust that fills the halo of the Milky Way galaxy 
A) the gas and dust that lie in between the stars in the Milky Way galaxy 
B) the middle section of the Milky Way galaxy 
C) the name of an oracle who can channel messages from beings that live near the star called Vega 
D) the dust that fills the halo of the Milky Way galaxy

Question 5

The Sun's location in the Milky Way Galaxy is _ .

Accepted Answer

A) very near the galactic center 
B) in the halo of the galaxy, about 28,000 light- years above the galactic disk 
C) at the very outer edge of the galactic disk 
D) in the galactic disk, roughly halfway between the center and the outer edge of the disk 
A) very near the galactic center 
B) in the halo of the galaxy, about 28,000 light- years above the galactic disk 
C) at the very outer edge of the galactic disk 
D) in the galactic disk, roughly halfway between the center and the outer edge of the disk

Question 6

Which of the following molecules is the most abundant in molecular clouds?

Accepted Answer

A) H2O 
B) H2 
C) CO 
D) NH3 
A) H2O 
B) H2 
C) CO 
D) NH3

Question 7

Suppose a scientist holds a press conference at which he claims that 10% of the matter in the Milky Way is in the form of dust grains. Does his claim seem reasonable? Why or why not?

Accepted Answer

A) The 10% figure is too high because there are not enough heavy elements to make that much dust. 
B) The 10% figure is too low because most of the mass of the galaxy is in the form of interstellar dust. 
C) It is reasonable because we already know that interstellar dust obscures our view through the disk of the galaxy. 
D) It seems reasonable as long as we assume that red giant stars-which produce dust grains in their stellar winds-are more common than we thought. 
A) The 10% figure is too high because there are not enough heavy elements to make that much dust. 
B) The 10% figure is too low because most of the mass of the galaxy is in the form of interstellar dust. 
C) It is reasonable because we already know that interstellar dust obscures our view through the disk of the galaxy. 
D) It seems reasonable as long as we assume that red giant stars-which produce dust grains in their stellar winds-are more common than we thought.

Question 8

What makes up the interstellar medium?

Accepted Answer

A) gas and dust 
B) K and M stars 
C) O and B stars 
D) open clusters 
E) all of the above 
A) gas and dust 
B) K and M stars 
C) O and B stars 
D) open clusters 
E) all of the above

Question 9

What elements do astronomers consider heavy elements?

Accepted Answer

A) elements that are heavier than iron 
B) elements that are heavier than hydrogen 
C) elements that are heavier than uranium 
D) elements that are heavier than carbon 
E) all elements besides hydrogen and helium 
A) elements that are heavier than iron 
B) elements that are heavier than hydrogen 
C) elements that are heavier than uranium 
D) elements that are heavier than carbon 
E) all elements besides hydrogen and helium

Question 10

All the following types of objects are found almost exclusively in the disk (rather than the halo)of the Milky Way except .

Accepted Answer

A) globular clusters 
B) X- ray binaries 
C) high- mass, red supergiant stars 
D) young stars 
A) globular clusters 
B) X- ray binaries 
C) high- mass, red supergiant stars 
D) young stars

Question 11

How does the diameter of the disk of Milky Way Galaxy compare to its thickness?

Accepted Answer

A) The diameter is about 100 times as great as the thickness. 
B) The diameter and thickness are roughly equal. 
C) The diameter is about 100,000 times as great as the thickness. 
D) The diameter is about 10 times as great as the thickness. 
A) The diameter is about 100 times as great as the thickness. 
B) The diameter and thickness are roughly equal. 
C) The diameter is about 100,000 times as great as the thickness. 
D) The diameter is about 10 times as great as the thickness.

Question 12

Suppose you want to observe and study the radiation from gas inside an interstellar bubble created by a supernova. Which of the following observatories will be most useful?

Accepted Answer

A) the Keck I telescope on the summit of Mauna Kea 
B) the Hubble Space Telescope 
C) the SOFIA airborne infrared observatory 
D) the Chandra X- ray Observatory 
A) the Keck I telescope on the summit of Mauna Kea 
B) the Hubble Space Telescope 
C) the SOFIA airborne infrared observatory 
D) the Chandra X- ray Observatory

Question 13

How would our view of our galaxy be different if we were located in the central bulge? What about if we were located in a halo globular cluster?

Accepted Answer

From within the central bulge of the gal

Question 14

Why do we believe that most of the mass of the Milky Way is in the form of dark matter?

Accepted Answer

A) Our view of distant galaxies is sometimes obscured by dark blotches in the sky, and we believe these blotches are dark matter located in the halo. 
B) Although dark matter emits no visible light, it can be seen with radio wavelengths, and such observations confirm that the halo is full of this material. 
C) The orbital speeds of stars far from the galactic center are surprisingly high, suggesting that these stars are feeling gravitational effects from unseen matter in the halo. 
D) Theoretical models of galaxy formation suggest that a galaxy cannot form unless it has at least 10 times as much matter as we see in the Milky Way disk, suggesting that the halo is full of dark matter. 
A) Our view of distant galaxies is sometimes obscured by dark blotches in the sky, and we believe these blotches are dark matter located in the halo. 
B) Although dark matter emits no visible light, it can be seen with radio wavelengths, and such observations confirm that the halo is full of this material. 
C) The orbital speeds of stars far from the galactic center are surprisingly high, suggesting that these stars are feeling gravitational effects from unseen matter in the halo. 
D) Theoretical models of galaxy formation suggest that a galaxy cannot form unless it has at least 10 times as much matter as we see in the Milky Way disk, suggesting that the halo is full of dark matter.

Question 15

What kinds of objects lie in the halo of our galaxy?

Accepted Answer

A) open clusters 
B) globular clusters 
C) O and B stars 
D) gas and dust 
E) all of the above 
A) open clusters 
B) globular clusters 
C) O and B stars 
D) gas and dust 
E) all of the above

Question 16

Over time, the star- gas- star cycle leads the gas in the Milky Way to .

Accepted Answer

A) become denser and hotter 
B) become denser and have a greater abundance of heavy elements 
C) have a lower abundance of heavy elements 
D) have a greater abundance of heavy elements 
A) become denser and hotter 
B) become denser and have a greater abundance of heavy elements 
C) have a lower abundance of heavy elements 
D) have a greater abundance of heavy elements

Question 17

What evidence suggests that most of the mass of the Milky Way is in the form of dark matter?

Accepted Answer

A) Theoretical models of galaxy formation suggest that a galaxy cannot form unless it has at least 10 times as much matter as we see in the Milky Way disk. 
B) Although dark matter emits no visible light, we have detected its radio emissions. 
C) The orbital speeds of stars far from the galactic center are surprisingly high. 
D) Our view of distant galaxies is often obscured by dark blotches, which are presumably made of dark matter. 
A) Theoretical models of galaxy formation suggest that a galaxy cannot form unless it has at least 10 times as much matter as we see in the Milky Way disk. 
B) Although dark matter emits no visible light, we have detected its radio emissions. 
C) The orbital speeds of stars far from the galactic center are surprisingly high. 
D) Our view of distant galaxies is often obscured by dark blotches, which are presumably made of dark matter.

Question 18

What is the best evidence for a supermassive black hole in the center of the Milky Way Galaxy?

Accepted Answer

A) amazing filaments of radio emission swirling around the center of the galaxy 
B) the gigantic bursts of X- ray energy from a mysterious dark object 
C) The existence of the Milky Way itself: The mass of the black hole is essential to gravitationally bind the galaxy together, so it doesn't fly apart. 
D) the motions of stars around a mysterious dark object 
A) amazing filaments of radio emission swirling around the center of the galaxy 
B) the gigantic bursts of X- ray energy from a mysterious dark object 
C) The existence of the Milky Way itself: The mass of the black hole is essential to gravitationally bind the galaxy together, so it doesn't fly apart. 
D) the motions of stars around a mysterious dark object

Question 19

Approximately how long does it take the Sun to orbit the center of the Milky Way Galaxy?

Accepted Answer

A) 2 billion years 
B) 200 million years 
C) 2 million years 
D) 200,000 years 
E) 20,000 years 
A) 2 billion years 
B) 200 million years 
C) 2 million years 
D) 200,000 years 
E) 20,000 years

Question 20

Open clusters and young stars are generally found only in the disk of the Milky Way and not in the halo.

Accepted Answer

A) True 
 B)False

About what percentage of the mass of a molecular cloud is in the form of dust?

What produces the striking red, blue, and black colors of ionization nebulae?

How do we learn about the conditions at the center of our own galaxy, the Milky Way?

What do we mean by the interstellar medium?

The Sun's location in the Milky Way Galaxy is _ .

Which of the following molecules is the most abundant in molecular clouds?

Suppose a scientist holds a press conference at which he claims that 10% of the matter in the Milky Way is in the form of dust grains. Does his claim seem reasonable? Why or why not?

What makes up the interstellar medium?

What elements do astronomers consider heavy elements?

All the following types of objects are found almost exclusively in the disk (rather than the halo)of the Milky Way except .

How does the diameter of the disk of Milky Way Galaxy compare to its thickness?

Suppose you want to observe and study the radiation from gas inside an interstellar bubble created by a supernova. Which of the following observatories will be most useful?

How would our view of our galaxy be different if we were located in the central bulge? What about if we were located in a halo globular cluster?

Why do we believe that most of the mass of the Milky Way is in the form of dark matter?

What kinds of objects lie in the halo of our galaxy?

Over time, the star- gas- star cycle leads the gas in the Milky Way to .

What evidence suggests that most of the mass of the Milky Way is in the form of dark matter?

What is the best evidence for a supermassive black hole in the center of the Milky Way Galaxy?

Approximately how long does it take the Sun to orbit the center of the Milky Way Galaxy?

Open clusters and young stars are generally found only in the disk of the Milky Way and not in the halo.

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: the New Science of Distant Worlds

Our Star

Surveying the Stars

Star Stuff

The Bizarre Stellar Graveyard

A Universe of Galaxies

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

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Exam 15: Our Galaxy

About what percentage of the mass of a molecular cloud is in the form of dust?

What produces the striking red, blue, and black colors of ionization nebulae?

How do we learn about the conditions at the center of our own galaxy, the Milky Way?

What do we mean by the interstellar medium?

The Sun's location in the Milky Way Galaxy is _ .

Which of the following molecules is the most abundant in molecular clouds?

Suppose a scientist holds a press conference at which he claims that 10% of the matter in the Milky Way is in the form of dust grains. Does his claim seem reasonable? Why or why not?

What makes up the interstellar medium?

What elements do astronomers consider heavy elements?

All the following types of objects are found almost exclusively in the disk (rather than the halo)of the Milky Way except .

How does the diameter of the disk of Milky Way Galaxy compare to its thickness?

Suppose you want to observe and study the radiation from gas inside an interstellar bubble created by a supernova. Which of the following observatories will be most useful?

How would our view of our galaxy be different if we were located in the central bulge? What about if we were located in a halo globular cluster?

Why do we believe that most of the mass of the Milky Way is in the form of dark matter?

What kinds of objects lie in the halo of our galaxy?

Over time, the star- gas- star cycle leads the gas in the Milky Way to .

What evidence suggests that most of the mass of the Milky Way is in the form of dark matter?

What is the best evidence for a supermassive black hole in the center of the Milky Way Galaxy?

Approximately how long does it take the Sun to orbit the center of the Milky Way Galaxy?

Open clusters and young stars are generally found only in the disk of the Milky Way and not in the halo.

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: the New Science of Distant Worlds

Our Star

Surveying the Stars

Star Stuff

The Bizarre Stellar Graveyard

A Universe of Galaxies

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

Filters