Question 1

The gas density in an emission nebula is typically about how many particles per cc?

Accepted Answer

A)  dozen 
B)  hundred 
C)  thousand 
D)  hundred thousand 
E)  million 
A)  dozen 
B)  hundred 
C)  thousand 
D)  hundred thousand 
E)  million

Question 2

The gas in the interstellar medium consists of mostly heavy elements.

Accepted Answer

A) True 
 B)False

Question 3

The most common molecule in a molecular cloud is:

Accepted Answer

A)  methane, CH₄. 
B)  molecular hydrogen, H₂. 
C)  carbon monoxide, CO. 
D)  water, H₂O. 
E)  ammonia, NH₃. 
A)  methane, CH₄. 
B)  molecular hydrogen, H₂. 
C)  carbon monoxide, CO. 
D)  water, H₂O. 
E)  ammonia, NH₃.

Question 4

The polarization of light passing though the dust grains shows that:

Accepted Answer

A)  the dust grains are elongated in shape. 
B)  the dust grains are aligned by a weak interstellar magnetic field. 
C)  the dust grains are chiefly made of iron. 
D)  Both A and B are correct. 
E)  All of the above are correct. 
A)  the dust grains are elongated in shape. 
B)  the dust grains are aligned by a weak interstellar magnetic field. 
C)  the dust grains are chiefly made of iron. 
D)  Both A and B are correct. 
E)  All of the above are correct.

Question 5

Emission nebulae are blue.

Accepted Answer

A) True 
 B)False

Question 6

Which of these is NOT a consequence of dust in the interstellar medium?

Accepted Answer

A)  reddening of stars' light that passes through the dust 
B)  blue reflection nebulae around the Pleiades 
C)  red light from the emission nebulae 
D)  the dark nebulae that block 90% of the Milky Way from us visually 
E)  terrestrial planets like our own 
A)  reddening of stars' light that passes through the dust 
B)  blue reflection nebulae around the Pleiades 
C)  red light from the emission nebulae 
D)  the dark nebulae that block 90% of the Milky Way from us visually 
E)  terrestrial planets like our own

Question 7

Why does a reflection nebula look blue?

Accepted Answer

The nebula is illuminated by t

Question 8

Most molecules found in the giant molecular clouds are based on silicon.

Accepted Answer

A) True 
 B)False

Question 9

A reflection nebula is caused by:

Accepted Answer

A)  starlight reflected off of a surface. 
B)  sunlight reflected off of a surface. 
C)  sunlight scattered by dust particles. 
D)  starlight scattered by dust particles. 
E)  emission by ionized gas. 
A)  starlight reflected off of a surface. 
B)  sunlight reflected off of a surface. 
C)  sunlight scattered by dust particles. 
D)  starlight scattered by dust particles. 
E)  emission by ionized gas.

Question 10

Interstellar gas is composed of:

Accepted Answer

A)  only hydrogen. 
B)  90% hydrogen, 9% helium by weight. 
C)  10% hydrogen, 90% helium by numbers of atoms. 
D)  some hydrogen, but mainly carbon dioxide. 
E)  ammonia, methane, and water vapor. 
A)  only hydrogen. 
B)  90% hydrogen, 9% helium by weight. 
C)  10% hydrogen, 90% helium by numbers of atoms. 
D)  some hydrogen, but mainly carbon dioxide. 
E)  ammonia, methane, and water vapor.

Question 11

What does the polarization of starlight tell us about the dust grains and the Galaxy?

Accepted Answer

The Galaxy's magnetic field al

Question 12

Contrast the chemical composition of interstellar gas with that of interstellar dust.

Accepted Answer

Gas is almost all hydrogen and

Question 13

Due to absorption of shorter wavelengths by interstellar dust clouds,distant stars appear:

Accepted Answer

A)  bluer. 
B)  brighter. 
C)  redder. 
D)  larger. 
E)  to have a higher radial velocity. 
A)  bluer. 
B)  brighter. 
C)  redder. 
D)  larger. 
E)  to have a higher radial velocity.

Question 14

Spectra of stars often show narrow absorption lines from interstellar matter.What type of interstellar matter produces these?

Accepted Answer

A)  dust 
B)  neutral gas 
C)  ionized gas 
D)  molecules 
E)  All of the above. 
A)  dust 
B)  neutral gas 
C)  ionized gas 
D)  molecules 
E)  All of the above.

Question 15

The ________ of light passing through thin dust clouds lets us map the Galaxy's magnetic field.

Accepted Answer

A)  diffraction 
B)  granulation 
C)  ionization 
D)  polarization 
E)  absorption 
A)  diffraction 
B)  granulation 
C)  ionization 
D)  polarization 
E)  absorption

Question 16

The "Local Bubble" is:

Accepted Answer

A)  created by our Sun's solar wind, and extends well past Pluto's orbit. 
B)  created by the bipolar jets of the young Sun, perpendicular to the ecliptic. 
C)  about 100 pcs. across and transparent to extreme ultraviolet radiation. 
D)  the region around the Milky Way where we can trace out its magnetic field. 
E)  the cluster of galaxies our Milky Way and M-31 in Andromeda belong to. 
A)  created by our Sun's solar wind, and extends well past Pluto's orbit. 
B)  created by the bipolar jets of the young Sun, perpendicular to the ecliptic. 
C)  about 100 pcs. across and transparent to extreme ultraviolet radiation. 
D)  the region around the Milky Way where we can trace out its magnetic field. 
E)  the cluster of galaxies our Milky Way and M-31 in Andromeda belong to.

Question 17

Explain the colors of emission nebulae.

Accepted Answer

The predominant bright red is the emissi

Question 18

There is as much mass in the voids between the stars as in the stars themselves.

Accepted Answer

A) True 
 B)False

Question 19

Most interstellar clouds are:

Accepted Answer

A)  much bigger than our solar system. 
B)  about the size of Earth. 
C)  similar in size to clouds in Earth's atmosphere. 
D)  much smaller than the clouds in Earth's atmosphere. 
E)  about the size of a wavelength of light. 
A)  much bigger than our solar system. 
B)  about the size of Earth. 
C)  similar in size to clouds in Earth's atmosphere. 
D)  much smaller than the clouds in Earth's atmosphere. 
E)  about the size of a wavelength of light.

Question 20

Which of the following has NOT yet been observed in space?

Accepted Answer

A)  formaldehyde 
B)  methyl alcohol 
C)  DNA 
D)  ammonia 
E)  hydrogen cyanide 
A)  formaldehyde 
B)  methyl alcohol 
C)  DNA 
D)  ammonia 
E)  hydrogen cyanide

Exam 18: The Interstellar Medium: Gas and Dust among the Stars

The gas density in an emission nebula is typically about how many particles per cc?

The gas in the interstellar medium consists of mostly heavy elements.

The most common molecule in a molecular cloud is:

The polarization of light passing though the dust grains shows that:

Emission nebulae are blue.

Which of these is NOT a consequence of dust in the interstellar medium?

Why does a reflection nebula look blue?

Most molecules found in the giant molecular clouds are based on silicon.

A reflection nebula is caused by:

Interstellar gas is composed of:

What does the polarization of starlight tell us about the dust grains and the Galaxy?

Contrast the chemical composition of interstellar gas with that of interstellar dust.

Due to absorption of shorter wavelengths by interstellar dust clouds,distant stars appear:

Spectra of stars often show narrow absorption lines from interstellar matter.What type of interstellar matter produces these?

The ________ of light passing through thin dust clouds lets us map the Galaxy's magnetic field.

The "Local Bubble" is:

Explain the colors of emission nebulae.

There is as much mass in the voids between the stars as in the stars themselves.

Most interstellar clouds are:

Which of the following has NOT yet been observed in space?

Charting the Heavens: The Foundations of Astronomy

The Copernican Revolution: The Birth of Modern Science

Radiation: Information from the Cosmos

Spectroscopy: The Inner Workings of Atoms

Telescopes: The Tools of Astronomy

The Solar System: Comparative Planetology and Formation Models

Earth: Our Home in Space

The Moon and Mercury: Scorched and Battered Worlds

Venus: Earth's Sister Planet

Mars: A Near Miss for Life?

Jupiter: Giant of the Solar System

Saturn: Spectacular Rings and Mysterious Moons

Uranus and Neptune: The Outer Worlds of the Solar System

Solar System Debris: Keys to Our Origin

Exoplanets: Planetary Systems Beyond Our Own

The Sun: Our Parent Star

The Stars: Giants,Dwarfs,and the Main Sequence

Star Formation: A Traumatic Birth

Stellar Evolution: The Life and Death of a Star

Stellar Explosions: Novae,Supernovae,and the Formation of the Elements

Neutron Stars and Black Holes: Strange States of Matter

The Milky Way Galaxy: A Spiral in Space

Galaxies: Building Blocks of the Universe

Galaxies and Dark Matter: The Large-Scale Structure of the Cosmos

Cosmology: The Big Bang and the Fate of the Universe

The Early Universe: Toward the Beginning of Time

Life in the Universe: Are We Alone?

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