Question 1

The Sun is located at the edge of the galaxy,approximately 50,000 light-years from the galactic center.

Accepted Answer

A) True 
 B)False

Question 2

What are cosmic rays?

Accepted Answer

A) subatomic particles that travel close to the speed of light 
B) gamma rays and X-rays 
C) fast-moving dust particles in the interstellar medium 
D) any light waves from space 
E) lasers used as weapons by extraterrestrials 
A) subatomic particles that travel close to the speed of light 
B) gamma rays and X-rays 
C) fast-moving dust particles in the interstellar medium 
D) any light waves from space 
E) lasers used as weapons by extraterrestrials

Question 3

If you were to take a voyage across the Milky Way,what kind of material would you spend most of your time in?

Accepted Answer

A) empty space-a pure vacuum 
B) dusty molecular clouds 
C) star clusters 
D) warm,rarefied clouds of atomic hydrogen 
E) cool,dense clouds of atomic hydrogen 
A) empty space-a pure vacuum 
B) dusty molecular clouds 
C) star clusters 
D) warm,rarefied clouds of atomic hydrogen 
E) cool,dense clouds of atomic hydrogen

Question 4

Shapley used the distribution of globular clusters in the galaxy to determine that the Sun was not at the center of the Milky Way.

Accepted Answer

A) True 
 B)False

Question 5

What do we call the bright,sphere-shaped region of stars that occupies the central few thousand light-years of the Milky Way Galaxy?

Accepted Answer

A) the galaxy's disk 
B) the galaxy's bulge 
C) a globular cluster 
D) the galaxy's halo 
A) the galaxy's disk 
B) the galaxy's bulge 
C) a globular cluster 
D) the galaxy's halo

Question 6

Where does most star formation occur in the Milky Way today?

Accepted Answer

A) in the halo 
B) in the bulge 
C) in the spiral arms 
D) in the Galactic center 
E) uniformly throughout the Galaxy 
A) in the halo 
B) in the bulge 
C) in the spiral arms 
D) in the Galactic center 
E) uniformly throughout the Galaxy

Question 7

What is an ionization nebula?

Accepted Answer

A) a region of very hot,low-density gas surrounding a recent supernova 
B) a clump of gas that will soon give birth to a new star 
C) a colorful cloud of gas that glows because it is heated by light from nearby hot stars 
D) a name sometimes used to describe spiral galaxies besides the Milky Way 
A) a region of very hot,low-density gas surrounding a recent supernova 
B) a clump of gas that will soon give birth to a new star 
C) a colorful cloud of gas that glows because it is heated by light from nearby hot stars 
D) a name sometimes used to describe spiral galaxies besides the Milky Way

Question 8

Why do spiral arms have a blue color?

Accepted Answer

Spiral arms are waves of enhanced densit

Question 9

What are cosmic rays?

Accepted Answer

A) another name for gamma rays and X-rays 
B) fast moving dust particles in the interstellar medium 
C) subatomic particles that travel close to the speed of light 
D) lasers used as weapons by extraterrestrials 
A) another name for gamma rays and X-rays 
B) fast moving dust particles in the interstellar medium 
C) subatomic particles that travel close to the speed of light 
D) lasers used as weapons by extraterrestrials

Question 10

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

Question 11

The average speed of stars relative to the Sun in the solar neighborhood is about 20 km/s.Suppose you discover a star in the solar neighborhood that is moving relative to the Sun at a much higher speed,say,200 km/s.What kind of orbit does this star probably have around the Milky Way? In what part of the galaxy does it spend most of its time? Explain.

Accepted Answer

Since stars that are traveling along wit

Question 12

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

Accepted Answer

A) Although dark matter emits no visible light,we have detected its radio emissions. 
B) The orbital speeds of stars far from the galactic center are surprisingly high. 
C) 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. 
D) Our view of distant galaxies is often obscured by dark blotches,which are presumably made of dark matter. 
A) Although dark matter emits no visible light,we have detected its radio emissions. 
B) The orbital speeds of stars far from the galactic center are surprisingly high. 
C) 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. 
D) Our view of distant galaxies is often obscured by dark blotches,which are presumably made of dark matter.

Question 13

If we could watch spiral arms from a telescope situated above the Milky Way over 500 million years,what would we see happen?

Accepted Answer

A) The spiral arms will seem to "wind up," to wrap more and more tightly around the center of the Galaxy. 
B) The spiral arms will eventually dissipate and fade away,since they are a temporary phenomenon that should only last for a million years or so. 
C) Stars will move through the spiral arms,bunching up closer as they pass through.Young hot stars will form and die within the arms before having a chance to move out. 
D) The spiral arms will eventually unwind,as centripetal forces send the stars flying outwards into intergalactic space. 
A) The spiral arms will seem to "wind up," to wrap more and more tightly around the center of the Galaxy. 
B) The spiral arms will eventually dissipate and fade away,since they are a temporary phenomenon that should only last for a million years or so. 
C) Stars will move through the spiral arms,bunching up closer as they pass through.Young hot stars will form and die within the arms before having a chance to move out. 
D) The spiral arms will eventually unwind,as centripetal forces send the stars flying outwards into intergalactic space.

Question 14

Elements heavier than hydrogen and helium constitute about ________ of the mass of the interstellar medium.

Accepted Answer

A) 0.002% 
B) 2% 
C) 70% 
D) 98% 
A) 0.002% 
B) 2% 
C) 70% 
D) 98%

Question 15

What is SgrA*?

Accepted Answer

A) a source of bright X-ray emission coming from the entire constellation of Sagittarius 
B) a source of bright radio emission in the center of our galaxy 
C) a source that is bright in the visible wavelengths in the center of our galaxy 
D) the brightest star in the constellation Sagittarius 
E) the bulge at the center of our galaxy 
A) a source of bright X-ray emission coming from the entire constellation of Sagittarius 
B) a source of bright radio emission in the center of our galaxy 
C) a source that is bright in the visible wavelengths in the center of our galaxy 
D) the brightest star in the constellation Sagittarius 
E) the bulge at the center of our galaxy

Question 16

Why are we unlikely to find Earth-like planets around halo stars in the Galaxy?

Accepted Answer

A) Planets around stars are known to be extremely rare. 
B) Halo stars formed in an environment where there were few heavy elements to create rocky planets. 
C) Any such planets would have been ejected long ago by galactic mergers. 
D) Halo stars do not have enough mass to hold onto planets. 
E) Halo stars formed in a different way from disk stars. 
A) Planets around stars are known to be extremely rare. 
B) Halo stars formed in an environment where there were few heavy elements to create rocky planets. 
C) Any such planets would have been ejected long ago by galactic mergers. 
D) Halo stars do not have enough mass to hold onto planets. 
E) Halo stars formed in a different way from disk stars.

Question 17

Observing the galaxy at radio wavelengths allows us to see beyond the dust in the disk of the galaxy that obscures our view.

Accepted Answer

A) True 
 B)False

Question 18

Which of the following statements is not true of the object known as Sgr A* in the center of our Galaxy?

Accepted Answer

A) It is by far the brightest source of visible light lying in the direction of the galactic center. 
B) It is thought to harbor a black hole of more than 3 million solar masses. 
C) It is a source of X-ray emission that we have observed with telescopes in space. 
D) It is a source of bright radio emission. 
A) It is by far the brightest source of visible light lying in the direction of the galactic center. 
B) It is thought to harbor a black hole of more than 3 million solar masses. 
C) It is a source of X-ray emission that we have observed with telescopes in space. 
D) It is a source of bright radio emission.

Question 19

Most of the current star formation in the Milky Way occurs in spiral arms.

Accepted Answer

A) True 
 B)False

Question 20

How do we learn about what is going on in the center of our own galaxy (the Milky Way)?

Accepted Answer

A) We have learned it only recently,thanks to the great photographs obtained by the Hubble Space Telescope. 
B) We cannot see the galactic center with visible or ultraviolet light,but radio and X-rays from the center can be detected. 
C) 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. 
D) We must look at the centers of other galaxies and hope that ours is just like others. 
E) We can study it with visible telescopes as with any other star in the Galaxy. 
A) We have learned it only recently,thanks to the great photographs obtained by the Hubble Space Telescope. 
B) We cannot see the galactic center with visible or ultraviolet light,but radio and X-rays from the center can be detected. 
C) 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. 
D) We must look at the centers of other galaxies and hope that ours is just like others. 
E) We can study it with visible telescopes as with any other star in the Galaxy.

Exam 19: Our Galaxy

The Sun is located at the edge of the galaxy,approximately 50,000 light-years from the galactic center.

What are cosmic rays?

If you were to take a voyage across the Milky Way,what kind of material would you spend most of your time in?

Shapley used the distribution of globular clusters in the galaxy to determine that the Sun was not at the center of the Milky Way.

What do we call the bright,sphere-shaped region of stars that occupies the central few thousand light-years of the Milky Way Galaxy?

Where does most star formation occur in the Milky Way today?

What is an ionization nebula?

Why do spiral arms have a blue color?

What are cosmic rays?

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?

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

If we could watch spiral arms from a telescope situated above the Milky Way over 500 million years,what would we see happen?

Elements heavier than hydrogen and helium constitute about ________ of the mass of the interstellar medium.

What is SgrA*?

Why are we unlikely to find Earth-like planets around halo stars in the Galaxy?

Observing the galaxy at radio wavelengths allows us to see beyond the dust in the disk of the galaxy that obscures our view.

Which of the following statements is not true of the object known as Sgr A* in the center of our Galaxy?

Most of the current star formation in the Milky Way occurs in spiral arms.

How do we learn about what is going on in the center of our own galaxy (the Milky Way)?

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 and Matter: Reading Messages from the Cosmos

Telescopes: Portals of Discovery

Our Planetary System

Formation of the Solar System

Planetary Geology: Earth and the Other Terrestrial Worlds

Planetary Atmospheres: Earth and the Other Terrestrial Worlds

Jovian Planet Systems

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 Birth

Star Stuff

The Bizarre Stellar Graveyard

Galaxies and the Foundations of Modern Cosmology

Galaxy Evolution

The Birth of the Universe

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

Life in the Universe

Celestial Timekeeping and Navigation

Space and Time

Spacetime and Gravity

Building Blocks of the Universe

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