Question 1

If I want to find a sizeable collection of Population II stars in the Milky Way Galaxy, where would be a good place to look?

Accepted Answer

A)  near the Sun 
B)  in a globular cluster high above the Galaxy's disk 
C)  in the Orion Spur 
D)  on the outer surface of giant molecular clouds 
E)  in an open cluster, especially one with a lot of dust in and around it 
A)  near the Sun 
B)  in a globular cluster high above the Galaxy's disk 
C)  in the Orion Spur 
D)  on the outer surface of giant molecular clouds 
E)  in an open cluster, especially one with a lot of dust in and around it B

Question 2

What leads astronomers to conclude that the proto-galactic cloud (the cloud from which our Galaxy formed) was roughly spherical?

Accepted Answer

A)  all black holes have spherical event horizons 
B)  the shape of the disk and spiral arm of the Milky Way Galaxy is spherical, so the original cloud must have been too 
C)  the oldest stars in the Galaxy (Population II stars, globular clusters) form a spherical halo around the Galaxy; they outline the original shape of the cloud that gave the Galaxy birth 
D)  since the Big Bang that made everything was spherical, all structures in the universe must also be spherical 
E)  actually, astronomers believe the original proto-galactic cloud was in the shape of a flat disk, like the Galaxy is now 
A)  all black holes have spherical event horizons 
B)  the shape of the disk and spiral arm of the Milky Way Galaxy is spherical, so the original cloud must have been too 
C)  the oldest stars in the Galaxy (Population II stars, globular clusters) form a spherical halo around the Galaxy; they outline the original shape of the cloud that gave the Galaxy birth 
D)  since the Big Bang that made everything was spherical, all structures in the universe must also be spherical 
E)  actually, astronomers believe the original proto-galactic cloud was in the shape of a flat disk, like the Galaxy is now C

Question 3

Our Milky Way Galaxy is what type of galaxy?

Accepted Answer

A)  spiral 
B)  elliptical 
C)  dwarf elliptical 
D)  irregular 
E)  none of the above 
A)  spiral 
B)  elliptical 
C)  dwarf elliptical 
D)  irregular 
E)  none of the above A

Question 4

Which of the following is evidence that the formation process of our Galaxy may have included collisions with smaller neighbor galaxies?

Accepted Answer

A)  the presence of millions of new stars, recently formed from clouds of gas and dust 
B)  the existence of supernova remnants, such as the Crab Nebula, in the Galaxy's disk 
C)  the observation that objects outside the orbit of the Sun are moving around the Galaxy faster than we expected 
D)  the observation that globular cluster are arranged in a spherical "halo" around the Galaxy 
E)  the observation of long moving streams of stars that continue to orbit through our Galaxy's halo 
A)  the presence of millions of new stars, recently formed from clouds of gas and dust 
B)  the existence of supernova remnants, such as the Crab Nebula, in the Galaxy's disk 
C)  the observation that objects outside the orbit of the Sun are moving around the Galaxy faster than we expected 
D)  the observation that globular cluster are arranged in a spherical "halo" around the Galaxy 
E)  the observation of long moving streams of stars that continue to orbit through our Galaxy's halo

Question 5

Where would you look for the youngest stars in the Milky Way Galaxy?

Accepted Answer

A)  in the halo 
B)  where there is dark matter 
C)  in the disk 
D)  in the nuclear bulge 
E)  you can't fool me; my chances of finding a very young star are the same, wherever in the Galaxy I look 
A)  in the halo 
B)  where there is dark matter 
C)  in the disk 
D)  in the nuclear bulge 
E)  you can't fool me; my chances of finding a very young star are the same, wherever in the Galaxy I look

Question 6

The scientist who made the first telescopic survey of the Milky Way and discovered that it is composed of a huge number of individual stars was

Accepted Answer

A)  Isaac Newton 
B)  Galileo Galilei 
C)  Edwin Hubble 
D)  Harlow Shapley 
E)  Jill Tarter 
A)  Isaac Newton 
B)  Galileo Galilei 
C)  Edwin Hubble 
D)  Harlow Shapley 
E)  Jill Tarter

Question 7

Astronomers now think that there is a black hole with more than 4 million times the mass of our Sun at the center of our Galaxy? Roughly how large would the event horizon of such a supermassive black hole be?

Accepted Answer

A)  the size of our Moon 
B)  about 4 light years across 
C)  about 17 times the size of the Sun 
D)  about the size of an atom (so much mass really compresses the event horizon) 
E)  we can't answer this question without knowing exactly what kind of stars were swallowed by the black hole 
A)  the size of our Moon 
B)  about 4 light years across 
C)  about 17 times the size of the Sun 
D)  about the size of an atom (so much mass really compresses the event horizon) 
E)  we can't answer this question without knowing exactly what kind of stars were swallowed by the black hole

Question 8

Astronomers today know a lot about the size and shape of the Milky Way Galaxy. Which of the following common objects most resembles the shape of our Galaxy?

Accepted Answer

A)  a beach ball 
B)  a flag, fluttering in the breeze 
C)  a CD or DVD 
D)  a cake 
E)  a glazed donut 
A)  a beach ball 
B)  a flag, fluttering in the breeze 
C)  a CD or DVD 
D)  a cake 
E)  a glazed donut

Question 9

Objects orbiting around the center of the Milky Way obey Kepler's 3rd Law. This means that:

Accepted Answer

A)  the pull of gravity gets stronger and stronger as you get further away from the center 
B)  larger clusters of stars will orbit the center more quickly than smaller ones 
C)  the closer a star is to the center, the longer it will take to go around 
D)  a cloud of gas or star that is further from the center will generally take more time to orbit 
E)  the orbits of all objects around the Galaxy are in the shape of a perfect circle 
A)  the pull of gravity gets stronger and stronger as you get further away from the center 
B)  larger clusters of stars will orbit the center more quickly than smaller ones 
C)  the closer a star is to the center, the longer it will take to go around 
D)  a cloud of gas or star that is further from the center will generally take more time to orbit 
E)  the orbits of all objects around the Galaxy are in the shape of a perfect circle

Question 10

Which of the following is NOT part of the growing chain of evidence that makes many astronomers suspect there is a black hole at the very center of the Milky Way Galaxy?

Accepted Answer

A)  the motion of stars close to the center indicates that there is a mass of 4.6 million solar masses inside their orbits 
B)  the Hubble Space Telescope has shown us a visible-light image of an accretion disk at the center of the Galaxy 
C)  the existence of a strong radio source at the center whose size appears to be no larger than Jupiter's orbit 
D)  the fact that Sagittarius A is a stationary radio source, while objects around it appear to be in motion 
E)  the observation that matter in the central region continues to be falling in toward the center 
A)  the motion of stars close to the center indicates that there is a mass of 4.6 million solar masses inside their orbits 
B)  the Hubble Space Telescope has shown us a visible-light image of an accretion disk at the center of the Galaxy 
C)  the existence of a strong radio source at the center whose size appears to be no larger than Jupiter's orbit 
D)  the fact that Sagittarius A is a stationary radio source, while objects around it appear to be in motion 
E)  the observation that matter in the central region continues to be falling in toward the center

Question 11

William Herschel thought that the Sun and Earth were roughly at the center of the great grouping of stars we call the Milky Way. Today we know this is not the case. What was a key reason that Herschel did not realize our true position in the Milky Way?

Accepted Answer

A)  he did not have a telescope, and most stars are too far away to see without a telescope 
B)  his telescope was only able to show him objects inside the solar system, and not objects in the Galaxy 
C)  the dust that extends throughout the disk of the Galaxy only allowed Herschel to see the small part of the Milky Way that surrounds us 
D)  there are so many black holes in the Galaxy, that they absorb a substantial part of the light from distant objects; we needed x-ray astronomy to see to more distant regions 
E)  Herschel shared with ancient people the firm religious belief that we must be the center of everything 
A)  he did not have a telescope, and most stars are too far away to see without a telescope 
B)  his telescope was only able to show him objects inside the solar system, and not objects in the Galaxy 
C)  the dust that extends throughout the disk of the Galaxy only allowed Herschel to see the small part of the Milky Way that surrounds us 
D)  there are so many black holes in the Galaxy, that they absorb a substantial part of the light from distant objects; we needed x-ray astronomy to see to more distant regions 
E)  Herschel shared with ancient people the firm religious belief that we must be the center of everything

Question 12

In the future, astronomers believe that the Milky Way Galaxy has additional collisions in store. Which of the following nearby galaxies are eventually going to collide with our own?

Accepted Answer

A)  the Small Magellanic Cloud 
B)  the Large Magellanic Cloud 
C)  the Andromeda Galaxy (M-31) 
D)  all of the above 
E)  none of the above 
A)  the Small Magellanic Cloud 
B)  the Large Magellanic Cloud 
C)  the Andromeda Galaxy (M-31) 
D)  all of the above 
E)  none of the above

Question 13

Radio astronomy has played a pivotal role in showing us the detailed structure of the Milky Way Galaxy. Which of the following techniques would a radio astronomer use as an essential part of an investigation of this structure?

Accepted Answer

A)  measuring the Doppler shift of a line in a radio spectrum 
B)  taking a photograph of the sky in the direction of the Big Dipper 
C)  using a CCD and a filter to record the amount of light from the stars in a nearby open cluster 
D)  measuring the amount of synchrotron radiation from the Crab Nebula 
E)  measuring the amount of radio radiation coming from the direction of Jupiter and other planets in the solar system 
A)  measuring the Doppler shift of a line in a radio spectrum 
B)  taking a photograph of the sky in the direction of the Big Dipper 
C)  using a CCD and a filter to record the amount of light from the stars in a nearby open cluster 
D)  measuring the amount of synchrotron radiation from the Crab Nebula 
E)  measuring the amount of radio radiation coming from the direction of Jupiter and other planets in the solar system

Question 14

Astronomers making observations in our Galaxy have been able to rule out a number of suggestions for what the dark matter in the Galaxy might be. Which of the following have we NOT been able to rule out (which suggestion is still "in the running")?

Accepted Answer

A)  black holes 
B)  hydrogen gas that is at low temperatures compared to stars 
C)  Jupiter-mass planets or brown dwarfs 
D)  large quantities of dust (like we find in nebulae) 
E)  a new kind of subatomic particle
Section 25.4: The Center of the Galaxy 
A)  black holes 
B)  hydrogen gas that is at low temperatures compared to stars 
C)  Jupiter-mass planets or brown dwarfs 
D)  large quantities of dust (like we find in nebulae) 
E)  a new kind of subatomic particle
Section 25.4: The Center of the Galaxy

Question 15

Astronomers now know that surrounding the main body of our Galaxy (which our various kinds of telescopes have shown to us) and our fainter halo of stars there is

Accepted Answer

A)  only the empty space that lies between galaxies 
B)  a series of hundreds and hundreds of nearby small galaxies, held in place by the Milky Way's gravity 
C)  an invisible halo made of what astronomers are calling "dark matter" 
D)  a set of huge clouds with many interesting molecules (like alcohol, carbon monoxide, and ammonia) in them 
E)  a pair of long, bright jets of materials produced by a massive black hole and its accretion disk 
A)  only the empty space that lies between galaxies 
B)  a series of hundreds and hundreds of nearby small galaxies, held in place by the Milky Way's gravity 
C)  an invisible halo made of what astronomers are calling "dark matter" 
D)  a set of huge clouds with many interesting molecules (like alcohol, carbon monoxide, and ammonia) in them 
E)  a pair of long, bright jets of materials produced by a massive black hole and its accretion disk

Question 16

Astronomers observe the Small Magellanic Cloud (SMC), a not very dense, rather small galaxy near us. They notice that even those stars that formed recently have relatively few heavier elements (when compared to such recent stars in our Milky Way.) What is the likely explanation for this deficiency?

Accepted Answer

A)  most stars in the SMC don't produce their energy through the process of nuclear fusion 
B)  most stars in the SMC finished going through their lives many billions of years ago 
C)  because the SMC is small and its stars are widely spaced, the rate of star formation (and star death) is much slower there 
D)  in small galaxies, only low-mass stars can form (and these do not produce supernovae) 
E)  astronomers cannot come up with any explanation for this puzzling observation 
A)  most stars in the SMC don't produce their energy through the process of nuclear fusion 
B)  most stars in the SMC finished going through their lives many billions of years ago 
C)  because the SMC is small and its stars are widely spaced, the rate of star formation (and star death) is much slower there 
D)  in small galaxies, only low-mass stars can form (and these do not produce supernovae) 
E)  astronomers cannot come up with any explanation for this puzzling observation

Question 17

Your weird cousin, who is really into astronomy, decides that the return address he uses on his letters is incomplete! To his city, state, and country, he begins to add: "North America, Earth, Solar System..." If he now wants to include the name of the Galaxy's spiral-structure feature in which the Earth is located, how should his address end?

Accepted Answer

A)  Cygnus Arm 
B)  Orion Spur 
C)  Perseus Arm 
D)  Sagittarius-Carina Arm 
E)  Mars arm
Section 25.3: The Mass of the Galaxy 
A)  Cygnus Arm 
B)  Orion Spur 
C)  Perseus Arm 
D)  Sagittarius-Carina Arm 
E)  Mars arm
Section 25.3: The Mass of the Galaxy

Question 18

The very strong source of radio waves at the center of our Galaxy is called

Accepted Answer

A)  Sagittarius A 
B)  Cygnus X-1 
C)  the Crab Nebula 
D)  Milky Way CC1 
E)  Benford G1 
A)  Sagittarius A 
B)  Cygnus X-1 
C)  the Crab Nebula 
D)  Milky Way CC1 
E)  Benford G1

Question 19

Which of the following statements about dark matter in the Galaxy is FALSE?

Accepted Answer

A)  Most of it cannot at present be observed with our telescopes (we only know its existence from the gravity it exerts) 
B)  While the dark matter cannot be observed with our present-day instruments, we still have a pretty good idea what it consist of 
C)  Our measurements suggest that there may be as much as ten or twenty times more dark matter in the Galaxy than the matter we have been able to observe 
D)  Dark matter appears to be distributed in a giant halo (outer layer) around the Galaxy 
E)  We can pretty much rule out the idea that the dark matter is made mainly of vast clouds or regions of hydrogen gas 
A)  Most of it cannot at present be observed with our telescopes (we only know its existence from the gravity it exerts) 
B)  While the dark matter cannot be observed with our present-day instruments, we still have a pretty good idea what it consist of 
C)  Our measurements suggest that there may be as much as ten or twenty times more dark matter in the Galaxy than the matter we have been able to observe 
D)  Dark matter appears to be distributed in a giant halo (outer layer) around the Galaxy 
E)  We can pretty much rule out the idea that the dark matter is made mainly of vast clouds or regions of hydrogen gas

Question 20

Recently, astronomers have observed stars and other objects that orbit the center of the Milky Way Galaxy farther out than our Sun, but move around faster than we do. How do astronomers think such an observation can be explained?

Accepted Answer

A)  all these faster-moving objects must be escaping from the gravity of the Milky Way and will soon be lost to our Galaxy 
B)  each of the faster-moving outer objects must be the result of a supernova explosion (giving them extra speed) 
C)  it is the Sun that is moving too slowly because of a collision billions of years ago; the outer objects are really moving at the appropriate speed for their distance from the center 
D)  there must be a great deal of invisible dark matter outside the orbit of the Sun whose gravitational pull explains the faster motions we see out there 
E)  no one can come up with any explanation for this puzzling observation 
A)  all these faster-moving objects must be escaping from the gravity of the Milky Way and will soon be lost to our Galaxy 
B)  each of the faster-moving outer objects must be the result of a supernova explosion (giving them extra speed) 
C)  it is the Sun that is moving too slowly because of a collision billions of years ago; the outer objects are really moving at the appropriate speed for their distance from the center 
D)  there must be a great deal of invisible dark matter outside the orbit of the Sun whose gravitational pull explains the faster motions we see out there 
E)  no one can come up with any explanation for this puzzling observation

Exam 25: The Milky Way Galaxy

If I want to find a sizeable collection of Population II stars in the Milky Way Galaxy, where would be a good place to look?

What leads astronomers to conclude that the proto-galactic cloud (the cloud from which our Galaxy formed) was roughly spherical?

Our Milky Way Galaxy is what type of galaxy?

Which of the following is evidence that the formation process of our Galaxy may have included collisions with smaller neighbor galaxies?

Where would you look for the youngest stars in the Milky Way Galaxy?

The scientist who made the first telescopic survey of the Milky Way and discovered that it is composed of a huge number of individual stars was

Astronomers now think that there is a black hole with more than 4 million times the mass of our Sun at the center of our Galaxy? Roughly how large would the event horizon of such a supermassive black hole be?

Astronomers today know a lot about the size and shape of the Milky Way Galaxy. Which of the following common objects most resembles the shape of our Galaxy?

Objects orbiting around the center of the Milky Way obey Kepler's 3rd Law. This means that:

Which of the following is NOT part of the growing chain of evidence that makes many astronomers suspect there is a black hole at the very center of the Milky Way Galaxy?

William Herschel thought that the Sun and Earth were roughly at the center of the great grouping of stars we call the Milky Way. Today we know this is not the case. What was a key reason that Herschel did not realize our true position in the Milky Way?

In the future, astronomers believe that the Milky Way Galaxy has additional collisions in store. Which of the following nearby galaxies are eventually going to collide with our own?

Radio astronomy has played a pivotal role in showing us the detailed structure of the Milky Way Galaxy. Which of the following techniques would a radio astronomer use as an essential part of an investigation of this structure?

Astronomers making observations in our Galaxy have been able to rule out a number of suggestions for what the dark matter in the Galaxy might be. Which of the following have we NOT been able to rule out (which suggestion is still "in the running")?

Astronomers now know that surrounding the main body of our Galaxy (which our various kinds of telescopes have shown to us) and our fainter halo of stars there is

Astronomers observe the Small Magellanic Cloud (SMC), a not very dense, rather small galaxy near us. They notice that even those stars that formed recently have relatively few heavier elements (when compared to such recent stars in our Milky Way.) What is the likely explanation for this deficiency?

The very strong source of radio waves at the center of our Galaxy is called

Which of the following statements about dark matter in the Galaxy is FALSE?

Recently, astronomers have observed stars and other objects that orbit the center of the Milky Way Galaxy farther out than our Sun, but move around faster than we do. How do astronomers think such an observation can be explained?

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

Between the Stars

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

Galaxies

Active Galaxies, Quasars, and Supermassive Black Holes

The Evolution and Distribution of Galaxies

The Big Bang

Life in the Universe

Filters