Question 1

Where is the outer rim of the Local Bubble located today?

Accepted Answer

A)  pretty much where Pluto orbits the Sun 
B)  about 200 light-years from the Sun, in the rough direction of the constellations of Orion, Perseus, and Auriga 
C)  at the edge of the Milky Way Galaxy 
D)  at the edge of the Orion Nebula 
E)  where else? Bayonne, New Jersey 
A)  pretty much where Pluto orbits the Sun 
B)  about 200 light-years from the Sun, in the rough direction of the constellations of Orion, Perseus, and Auriga 
C)  at the edge of the Milky Way Galaxy 
D)  at the edge of the Orion Nebula 
E)  where else? Bayonne, New Jersey

Question 2

Astronomers have found large quantities of cold, neutral hydrogen gas in our galaxy. How is this gas distributed?

Accepted Answer

A)  it is located only near stars, and not in the large empty spaces between them 
B)  it is found mostly in a flat layer extending throughout the disk of our galaxy 
C)  it is found in a spherical distribution about 100 LY in size, centered on the Sun 
D)  it is found only in the outer regions of the galaxy, where we are, and not in the central areas 
E)  we don't know its distribution, since such cold hydrogen cannot be observed with the techniques we have at our disposal today 
A)  it is located only near stars, and not in the large empty spaces between them 
B)  it is found mostly in a flat layer extending throughout the disk of our galaxy 
C)  it is found in a spherical distribution about 100 LY in size, centered on the Sun 
D)  it is found only in the outer regions of the galaxy, where we are, and not in the central areas 
E)  we don't know its distribution, since such cold hydrogen cannot be observed with the techniques we have at our disposal today

Question 3

An astronomer is observing a star which puzzles her. The lines in the star's spectrum indicates that the star is very hot and should therefore be blue. But the star looks reddish in photographs and in measurements of the continuous spectrum. What is one possible explanation of this puzzle?

Accepted Answer

A)  this star is surrounded by an HII region 
B)  this star is in a local bubble, just like the Sun 
C)  the star is no longer undergoing nuclear fusion inside 
D)  we are seeing the light of the star through layers of interstellar dust 
E)  this star must be located high above the disk of the Milky Way Galaxy 
A)  this star is surrounded by an HII region 
B)  this star is in a local bubble, just like the Sun 
C)  the star is no longer undergoing nuclear fusion inside 
D)  we are seeing the light of the star through layers of interstellar dust 
E)  this star must be located high above the disk of the Milky Way Galaxy

Question 4

An HII region is

Accepted Answer

A)  a zone around a hot star where hydrogen atoms are ionized 
B)  a place where there is mostly neutral hydrogen whose spectral lines we observe 
C)  a cloud of dark dust, which absorbs much of the starlight coming from behind it 
D)  one of the large and cold molecular clouds where we see star formation going on 
E)  a cloud of complex molecules, such as alcohol and formaldehyde 
A)  a zone around a hot star where hydrogen atoms are ionized 
B)  a place where there is mostly neutral hydrogen whose spectral lines we observe 
C)  a cloud of dark dust, which absorbs much of the starlight coming from behind it 
D)  one of the large and cold molecular clouds where we see star formation going on 
E)  a cloud of complex molecules, such as alcohol and formaldehyde

Question 5

Cosmic rays differ from other forms of interstellar matter by

Accepted Answer

A)  moving much faster, at typical speeds of 90% the speed of light 
B)  being made of hydrogen atoms 
C)  absorbing all the light that falls on them 
D)  having nothing to do with stars at any point in their "lives" 
E)  coming only from outside the Milky Way Galaxy 
A)  moving much faster, at typical speeds of 90% the speed of light 
B)  being made of hydrogen atoms 
C)  absorbing all the light that falls on them 
D)  having nothing to do with stars at any point in their "lives" 
E)  coming only from outside the Milky Way Galaxy

Question 6

Supposing we launched a very fast dart from the Space Shuttle, pointed in some direction away from any planet, so that it could travel beyond the solar system. What would it be most likely to hit first after traveling outward for a while?

Accepted Answer

A)  a star other than the Sun 
B)  an exoplanet 
C)  an atom of interstellar gas 
D)  another galaxy 
E)  its chances of intersecting all of the above is about the same
Section 20.2: Interstellar Gas 
A)  a star other than the Sun 
B)  an exoplanet 
C)  an atom of interstellar gas 
D)  another galaxy 
E)  its chances of intersecting all of the above is about the same
Section 20.2: Interstellar Gas

Question 7

In order for a cold atom of hydrogen to emit a 21-cm wave, it must first be in a slightly higher energy state. What event usually "kicks" the hydrogen atom up to this higher state?

Accepted Answer

A)  waves of ultraviolet energy from hot stars pass by a cold gas cloud 
B)  a gas cloud collapses under its own gravity until it is much smaller than it originally was 
C)  gas atoms within the cloud collide 
D)  hydrogen is ionized by other waves 
E)  some alcohol molecules within the cloud lead to a wild party 
A)  waves of ultraviolet energy from hot stars pass by a cold gas cloud 
B)  a gas cloud collapses under its own gravity until it is much smaller than it originally was 
C)  gas atoms within the cloud collide 
D)  hydrogen is ionized by other waves 
E)  some alcohol molecules within the cloud lead to a wild party

Question 8

Astronomers were at first surprised to find complicated molecules in the interstellar medium. They thought ultra-violet light from stars would break apart such molecules. What protects the molecules we observe from being broken apart?

Accepted Answer

A)  such molecules form in cells, and there is a protective membrane around each cell 
B)  such molecules always form inside stars; the stars outer layers protect them 
C)  such molecules form in clouds that contain significant amounts of dust, and the dust in the cloud protects them from ultra-violet rays 
D)  such molecules form only in the regions that are already millions of degrees hot and thus can't be affected by ultra-violet rays 
E)  you can't fool me; the seeming discovery of complex molecules out there was a mistake, and astronomers now realize there are no molecules out there. 
A)  such molecules form in cells, and there is a protective membrane around each cell 
B)  such molecules always form inside stars; the stars outer layers protect them 
C)  such molecules form in clouds that contain significant amounts of dust, and the dust in the cloud protects them from ultra-violet rays 
D)  such molecules form only in the regions that are already millions of degrees hot and thus can't be affected by ultra-violet rays 
E)  you can't fool me; the seeming discovery of complex molecules out there was a mistake, and astronomers now realize there are no molecules out there.

Question 9

The amount of interstellar matter present in our Galaxy is always changing. Which of the following processes is NOT a major contributor to that change?

Accepted Answer

A)  gas from outside the Galaxy falls into the Milky Way because of gravity 
B)  the powerful explosions that end the lives of massive stars drive material out of the Galaxy 
C)  interstellar matter in dense clouds collapses into stars and is taken "out of circulation" 
D)  some atoms of gas combine in dusty clouds to make more complex molecules 
E)  actually, none of the above is a major contributor to the change 
A)  gas from outside the Galaxy falls into the Milky Way because of gravity 
B)  the powerful explosions that end the lives of massive stars drive material out of the Galaxy 
C)  interstellar matter in dense clouds collapses into stars and is taken "out of circulation" 
D)  some atoms of gas combine in dusty clouds to make more complex molecules 
E)  actually, none of the above is a major contributor to the change

Question 10

An astronomer wants to observe a cloud of cold neutral (not ionized) hydrogen, far away from any stars. What would be an instrument that could help in this task?

Accepted Answer

A)  a telescope in space, able to pick up x-rays from space 
B)  a radio telescope, tuned to a wavelength of about 21 centimeters 
C)  a large telescope observing visible light, but with a very sensitive CCD detector attached 
D)  a neutrino detector, deep underground 
E)  you can't fool me; there is no way to observe clouds of hydrogen that are not near a star 
A)  a telescope in space, able to pick up x-rays from space 
B)  a radio telescope, tuned to a wavelength of about 21 centimeters 
C)  a large telescope observing visible light, but with a very sensitive CCD detector attached 
D)  a neutrino detector, deep underground 
E)  you can't fool me; there is no way to observe clouds of hydrogen that are not near a star

Question 11

The light element lithium (which, on Earth, is part of medications that improve the lives of people with mental health illnesses) is more common in cosmic rays than it is in the Sun and the stars. What do astronomers think is the reason for this?

Accepted Answer

A)  there is a lot of lithium (and other light elements) in interstellar dust 
B)  lithium is so easy to fuse, its fusion happens outside of stars in hot HII regions 
C)  because cosmic rays move so fast, they can collide with atoms of carbon, nitrogen, and oxygen and break them apart, producing more light elements like lithium 
D)  lithium is radioactive; its nucleus decays (falls apart) very quickly 
E)  this is an unsolved problem in astronomy
Section 20.5: The Life Cycle of Cosmic Material 
A)  there is a lot of lithium (and other light elements) in interstellar dust 
B)  lithium is so easy to fuse, its fusion happens outside of stars in hot HII regions 
C)  because cosmic rays move so fast, they can collide with atoms of carbon, nitrogen, and oxygen and break them apart, producing more light elements like lithium 
D)  lithium is radioactive; its nucleus decays (falls apart) very quickly 
E)  this is an unsolved problem in astronomy
Section 20.5: The Life Cycle of Cosmic Material

Question 12

You are observing a binary star system and obtain a series of spectra of the light from the two stars. In this spectrum, most of the absorption lines shift back and forth as expected from the Doppler Effect. A few lines, however, do not shift at all, but remain at the same wavelength. How can we explain the behavior of the non-shifting lines?

Accepted Answer

A)  there is a star in the system which is not moving at all: it is just sitting there 
B)  there is a planet orbiting the stars in the system 
C)  there are huge clouds of dust just behind this star system from our perspective 
D)  the lines come from interstellar matter between us and the star, not from the stars themselves 
E)  there is no explanation of this behavior: it is an unsolved mystery in science 
A)  there is a star in the system which is not moving at all: it is just sitting there 
B)  there is a planet orbiting the stars in the system 
C)  there are huge clouds of dust just behind this star system from our perspective 
D)  the lines come from interstellar matter between us and the star, not from the stars themselves 
E)  there is no explanation of this behavior: it is an unsolved mystery in science

Question 13

When astronomers discuss a nebula, what are they talking about?

Accepted Answer

A)  the Frisbee-shaped collection of gas that covers the entire Milky Way Galaxy 
B)  the cloud of comets that lies on the outskirts of the solar system 
C)  a giant cloud of gas and dust between or among the stars 
D)  a star surrounded by at least 8 planets and many moons 
E)  none of the above 
A)  the Frisbee-shaped collection of gas that covers the entire Milky Way Galaxy 
B)  the cloud of comets that lies on the outskirts of the solar system 
C)  a giant cloud of gas and dust between or among the stars 
D)  a star surrounded by at least 8 planets and many moons 
E)  none of the above

Question 14

Among interstellar clouds, the hotter the cloud, the

Accepted Answer

A)  the higher the density of particles in it 
B)  the smaller the diameter of the cloud must be 
C)  the lower the density of particles in it 
D)  less likely it is to contain ionized atoms 
E)  the more likely it is to contain vast quantities of complex molecules 
A)  the higher the density of particles in it 
B)  the smaller the diameter of the cloud must be 
C)  the lower the density of particles in it 
D)  less likely it is to contain ionized atoms 
E)  the more likely it is to contain vast quantities of complex molecules

Question 15

Astronomers use the term interstellar extinction to refer to:

Accepted Answer

A)  the death of the dinosaurs and other species from the collision of an asteroid with the Earth 
B)  the death of a massive star when it explodes 
C)  the ionization of a region of hydrogen around an extremely hot star 
D)  the absorption of radio waves at 21-cm by cold hydrogen atoms 
E)  the scattering and absorption of starlight by dust grains in space 
A)  the death of the dinosaurs and other species from the collision of an asteroid with the Earth 
B)  the death of a massive star when it explodes 
C)  the ionization of a region of hydrogen around an extremely hot star 
D)  the absorption of radio waves at 21-cm by cold hydrogen atoms 
E)  the scattering and absorption of starlight by dust grains in space

Question 16

Which of the following is NOT a way astronomers discover clouds of interstellar matter that have a large amount of dust in them?

Accepted Answer

A)  by blocking the light of stars behind them 
B)  by reflecting nearby starlight 
C)  because they make stars behind them look redder than they should be 
D)  by giving off infrared radiation appropriate to their temperature 
E)  by giving off x-rays from hot gas surrounding the dust cloud 
A)  by blocking the light of stars behind them 
B)  by reflecting nearby starlight 
C)  because they make stars behind them look redder than they should be 
D)  by giving off infrared radiation appropriate to their temperature 
E)  by giving off x-rays from hot gas surrounding the dust cloud

Question 17

Astronomers use the term interstellar matter to refer to:

Accepted Answer

A)  planets around stars other than the Sun 
B)  comets, asteroids, and meteors 
C)  gas and dust that lies between stars 
D)  electro-magnetic radiation coming from a group of stars 
E)  a fortune teller who says she is from outer space 
A)  planets around stars other than the Sun 
B)  comets, asteroids, and meteors 
C)  gas and dust that lies between stars 
D)  electro-magnetic radiation coming from a group of stars 
E)  a fortune teller who says she is from outer space

Exam 20: Between the Stars

Where is the outer rim of the Local Bubble located today?

Astronomers have found large quantities of cold, neutral hydrogen gas in our galaxy. How is this gas distributed?

An astronomer is observing a star which puzzles her. The lines in the star's spectrum indicates that the star is very hot and should therefore be blue. But the star looks reddish in photographs and in measurements of the continuous spectrum. What is one possible explanation of this puzzle?

An HII region is

Cosmic rays differ from other forms of interstellar matter by

Supposing we launched a very fast dart from the Space Shuttle, pointed in some direction away from any planet, so that it could travel beyond the solar system. What would it be most likely to hit first after traveling outward for a while?

In order for a cold atom of hydrogen to emit a 21-cm wave, it must first be in a slightly higher energy state. What event usually "kicks" the hydrogen atom up to this higher state?

Astronomers were at first surprised to find complicated molecules in the interstellar medium. They thought ultra-violet light from stars would break apart such molecules. What protects the molecules we observe from being broken apart?

The amount of interstellar matter present in our Galaxy is always changing. Which of the following processes is NOT a major contributor to that change?

An astronomer wants to observe a cloud of cold neutral (not ionized) hydrogen, far away from any stars. What would be an instrument that could help in this task?

The light element lithium (which, on Earth, is part of medications that improve the lives of people with mental health illnesses) is more common in cosmic rays than it is in the Sun and the stars. What do astronomers think is the reason for this?

When astronomers discuss a nebula, what are they talking about?

Among interstellar clouds, the hotter the cloud, the

Astronomers use the term interstellar extinction to refer to:

Which of the following is NOT a way astronomers discover clouds of interstellar matter that have a large amount of dust in them?

Astronomers use the term interstellar matter to refer to:

Science and the Universe: a Brief Tour

Observing the Sky: the Birth of Astronomy

Orbits and Gravity

Earth, Moon, and Sky

Radiation and Spectra

Astronomical Instruments

Other Worlds: an Introduction to the Solar System

Earth As a Planet

Cratered Worlds: the Moon and Mercury

Earthlike Planets: Venus and Mars

The Giant Planets

Rings, Moons, and Pluto

Comets and Asteroids: Debris of the Solar System

Cosmic Samples and the Origin of the Solar System

The Sun: a Garden-Variety Star

The Sun: a Nuclear Powerhouse

Analyzing Starlight

The Stars: a Celestial Census

Celestial Distances

The Birth of Stars and the Discovery of Planets Outside the Solar System

Stars From Adolescence to Old Age

The Death of Stars

Black Holes and Curved Space-Time

The Milky Way Galaxy

Galaxies

Active Galaxies, Quasars, and Supermassive Black Holes

The Evolution and Distribution of Galaxies

The Big Bang

Life in the Universe

Filters