Conceptual Quiz  Chapter 1
Part A
Which of the following has your "cosmic address" in the correct order?
Hint A.1
Review Figure 1.1.
ANSWER:

You, Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe You, Earth, solar system, Local Group, Milky Way Galaxy, Local Supercluster, universe You, Earth, Local Group, Local Supercluster, solar system, Milky Way Galaxy, universe You, Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, universe You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe
Part B
Using the ideas discussed in the text, in what sense are we "star stuff"?
Hint B.1
See Section 1.1 in the text.
ANSWER:

Movie stars and other people are all made of the same stuff, so we all have the potential to be famous. We could not survive without light from our star, the Sun. Nearly every atom from which we are made was once inside of a star. Our overall chemical composition is about the same as that of stars.
Part C
How are galaxies important to our existence?
Hint C.1
See Section 1.1 in the text.
ANSWER:

Without galaxies, the universe could not be expanding. Without galaxies, there could not have been a Big Bang. Deep in their centers, galaxies created the elements from which we are made. Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist.
Part D
When we look at an object that is 1,000 light-years away we see it _________.
Hint D.1
Study Section 1.1, and remember that a light-year is the distance light can travel in one year.
ANSWER:

looking just the same as our ancestors would have seen it 1,000 years ago as it is right now, but it appears 1,000 times dimmer as it was 1,000 years ago as it was 1,000 light-years ago
Part E
Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case _________.
Hint E.1
Study Section 1.1, and remember that the farther away we look in distance, the further back we look in time.
ANSWER:

we are seeing Galaxy 1 as it looked at a later time in the history of the universe than Galaxy 2 Galaxy 1 must be twice as big as Galaxy 2 we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2 Galaxy 2 must be twice as old as Galaxy 1
Part F
Suppose we make a scale model of our solar system, with the Sun the size of a grapefruit. Which of the following best describes what the planets would look like?
Hint F.1
Study Section 1.2.
ANSWER:

The planets range in size from about the size of a marble to the size of a baseball. They are spread out over a region about the size of a football field. They are all much smaller than the Sun. Four planets are within about 20 meters of the Sun, while the remaining planets are spread much farther apart, with Pluto more than a half a kilometer from the Sun. They are all much smaller than the Sun and are spread out evenly over a distance about the length of a large classroom. They are all much smaller than the Sun. Six planets are located within a few centimeters of the Sun, and three planets are located at distances ranging up to about a meter.
Part G
How long would it take to count all the stars in the Milky Way Galaxy at a rate of one star per second?
Hint G.1
Study Section 1.2, and remember that there are at least 100 billion stars in the Milky Way Galaxy.
ANSWER:

Several weeks Several years Several days Several thousand years
Part H
The total number of stars in the observable universe is about _________.
Hint H.1
See Section 1.2.
ANSWER:

100 billion the same as the number of grains of sand on all the beaches on Earth the same as the number of grains of sand in a large sandbox the same as the number of atoms that make up the Earth
Part I
Where is our solar system located within the Milky Way Galaxy?
Hint I.1
See Figure 1.1.
ANSWER:

At the far edge of the galaxy's visible disk Roughly halfway between the center and the edge of the visible disk of the galaxy In the halo of the galaxy Very near the center of the galaxy
Part J
If we imagine the history of the universe compressed into one year, the dinosaurs became extinct _________.
Hint J.1
Study the cosmic calendar in Section 1.2.
ANSWER:

yesterday about 3 weeks ago about an hour ago about 6 months ago
Part K
Relative to the age of the universe, how old is our solar system?
Hint K.1
Study the cosmic calendar in your text.
ANSWER:

It is between about 5% and 10% as old as the universe. It is between about one-quarter and one-half the age of the universe It is about the same age as the universe because it formed shortly after the Big Bang. It is about 1% as old as the universe.
Part L
How do the speeds at which we are moving with the Earth's rotation and orbit compare to the speeds of more familiar objects?
Hint L.1
See Section 1.3.
ANSWER:

The Earth's rotation is carrying most people around the axis faster than a commercial jet travels, and the Earth's orbit is carrying us around the Sun faster than the Space Shuttle orbits the Earth. The Earth's rotation is carrying most people around the axis at about the speed at which the Space Shuttle orbits the Earth, and the Earth's orbit is carrying us around the Sun at nearly the speed of light. The Earth's rotation is carrying most people around the axis at about the speed of a car on the freeway, and the Earth's orbit is carrying us around the Sun at about the speed of a commercial jet. The Earth's rotation is carrying most people around the axis at about the speed of a commercial jet, and the Earth's orbit is carrying us around the Sun at about the speed of a military jet.
Part M
Why do the patterns of the stars in our sky look the same from year to year?
Hint M.1
Study Section 1.3.
ANSWER:

Because although these stars are moving, they move so slowly --- typically about the speed of a snail --- that their motion is not noticeable. Although these stars move quite fast by human standards, they are so far away that it would take thousands of years for their motion to be noticeable to the eye. Because these stars are not moving. Because although these stars move quite fast as they orbit around the Milky Way Galaxy, they all move together so they don't change their relative positions.
Part N
Astronomers infer that the universe is expanding because distant galaxies all appear to _________.
Hint N.1
See Section 1.3.
ANSWER:

be made of dark matter be moving away from us, with more distant ones moving faster be growing in size rotate rapidly
Part O

These photos show two different astronomical objects. Which object is bigger, and by about how much?
Hint O.1
Be sure to think about the scale of each of the two objects shown.
ANSWER:

Object 2 is more than a trillion times as large as Object 1. Both objects are about the same size. Object 2 is about 10 times as large as Object 1. Object 2 is approximately 1,000 times as large as Object 1. Object 1 is about 10 times as large as Object 2.