MasteringAstronomy Chapter 1

Which of the following correctly lists our "cosmic address" from small to large? a. Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe; b. Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe; c. Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, universe.

*a. Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe;*

Could we see a galaxy that is 20 billion light-years away? a. Yes, if we had a big enough telescope. b. No, because it would be beyond the bounds of our observable universe. c. No, because a galaxy could not possibly be that far away.

*b. No, because it would be beyond the bounds of our observable universe.*

Define light-year. a. The distance that Earth travels around the Sun in 1 year, which is about 9.46 million kilometers. b. The distance that light can travel in 1 year, which is approximately 149.6 billion kilometers. c. The distance that light travels in 1 year, which is about 9.46 trillion kilometers. d. The distance that light can travel in 1 year, which is approximately 149.6 trillion kilometers. e. The average distance between Earth and the Sun, which is about 9.46 billion kilometers.

*c. The distance that light travels in 1 year, which is about 9.46 trillion kilometers.*

The star Betelgeuse is about 600 light-years away. If it explodes tonight, a. we'll know because debris from the explosion will rain down on us from space. b. we'll know because it will be brighter than the full Moon in the sky. c. we won't know about it until about 600 years from now.

*c. we won't know about it until about 600 years from now.*

Define astronomical unit. a. The distance that light can travel in 1 year, which is approximately 149.6 billion kilometers. b. The average distance between the Sun and Neptune, which is approximately 4497 million kilometers. c. The average distance between Earth and the Sun, which is about 9.46 billion kilometers. d. The average distance between Earth and the Sun, which is approximately 149.6 million kilometers. e. The distance that Earth travels around the Sun in 1 year, which is about 9.46 million kilometers.

*d. The average distance between Earth and the Sun, which is approximately 149.6 million kilometers.*

Represent 1 light-hour in kilometers. Express your answer using three significant figures.

1 light-hour =1.08×10^9km

Represent 1 light-hour in miles. Express your answer using three significant figures.

1 light-hour =6.71×10^8mi

Represent 2 light-seconds in miles. Express your answer using three significant figures.

2 light-seconds =3.73×10^5mi

Represent 2 light-seconds in kilometers. Express your answer using three significant figures.

2 light-seconds =6.00×10^5km

Represent 3 light-days in miles. Express your answer using three significant figures.

3 light-days =4.83×10^10mi

Represent 3 light-days in kilometers. Express your answer using three significant figures.

3 light-days =7.78×10^10km

Represent 4 light-minutes in miles. Express your answer using three significant figures.

4 light-minutes =4.47×10^7mi

Represent 4 light-minutes in kilometers. Express your answer using three significant figures.

4 light-minutes =7.20×10^7km

Note that an observer located at the Local Raisin would see Raisins 1, 2, and 3 all move away from her during the video. What would an observer located at Raisin 2 see? a. Raisin 1 and Raisin 3 both move away from her. b. Raisin 1 and Raisin 3 both move toward her. c. Raisin 1 moves away from her while Raisin 3 moves toward her. d. Raisin 1 moves toward her while Raisin 3 moves away from her.

a. Raisin 1 and Raisin 3 both move away from her.

Which of the following statements best describes what astronomers mean when they say that the universe is expanding? a. The average distance between galaxies is increasing with time. b. The observable universe is growing larger in radius at a rate of one light-year per year. c. The universe itself is not growing, but our knowledge of the universe is increasing with time. d. All objects in the universe, including Earth and everything on it, are gradually growing in size. e. The average distance between stars in the Milky Way Galaxy is increasing with time.

a. The average distance between galaxies is increasing with time.

The fact that nearly all galaxies are moving away from us, with more distant ones moving faster, helped us to conclude that: a. The universe is expanding. b. Galaxies repel each other like magnets. c. Our galaxy lies near the center of the universe.

a. The universe is expanding.

Today, the evidence that we live in an expanding universe is extremely strong because astronomers have measured the motions of millions of galaxies. Nevertheless, in science, we must always remain open to the possibility that some future observation could call even our most strongly supported theories into question. Which of the following hypothetical observations would not be consistent with what we expect in an expanding universe? a. You discover an extremely distant galaxy that is moving toward us. b. You discover a pair of distant galaxies that are colliding with one another. c. You discover an extremely distant galaxy that is moving away from us at 90% of the speed of light.

a. You discover an extremely distant galaxy that is moving toward us.

According to current scientific estimates, when did the Big Bang occur? a. about 20 billion years ago b. about 14 billion years ago c. about 10 billion years ago d. about 4 1/2 billion years ago e. about 65 million years ago

b. about 14 billion years ago

Based on what you've learned from the raisin cake analogy, which two properties of distant galaxies do astronomers have to measure to show that we live in an expanding universe? View Available Hint(s) a. their ages and distances b. their distances and speeds c. their ages and masses d. their distances and masses

b. their distances and speeds

If stars existed but galaxies did not: a. We would probably still exist anyway. b. We would not exist because life on Earth depends on the light produced by galaxies. c. We would not exist because we are made of material that required recycling in galaxies.

c. We would not exist because we are made of material that required recycling in galaxies.

On the cosmic calendar, which compresses the history of the universe into a single year, about when did life arise on Earth? a. in late January b. in mid-August c. in September d. in mid-December e. just a few hours before midnight on December 31

c. in September

The following statements describe ways in which the analogy might apply to the real universe. Which statements are correct? Check all that apply. a. The temperature starts low and ends high in both the raisin cake and the universe. b. Both the raisin cake and the universe have a well-defined inside and outside. c. Raisin 1 is near the center of the cake, just as our galaxy is near the center of the universe. d. The average distance increases with time both between raisins in the cake and between galaxies in the universe. e. An observer at any raisin sees more distant raisins moving away faster, just as an observer in any galaxy sees more distant galaxies moving away faster. f. The raisins stay roughly the same size as the cake expands, just as galaxies stay roughly the same size as the universe expands.

d. The average distance increases with time both between raisins in the cake and between galaxies in the universe. e. An observer at any raisin sees more distant raisins moving away faster, just as an observer in any galaxy sees more distant galaxies moving away faster. f. The raisins stay roughly the same size as the cake expands, just as galaxies stay roughly the same size as the universe expands.

On the cosmic calendar, which compresses the history of the universe into a single year, about when did Earth form? a. very early in January b. in mid-February c. in June d. in early September e. in mid-December

d. in early September

The table in the video shows you the speeds of Raisins 1, 2, and 3 as measured from the Local Raisin. Suppose instead that you measured speeds as seen from Raisin 2. An observer at Raisin 2 would measure __________. a. Local Raisin speed = 4.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 4.0 cm/hr b. Local Raisin speed = 2.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 2.0 cm/hr c. Local Raisin speed = 6.0 cm/hr; Raisin 1 speed = 4.0 cm/hr; Raisin 3 speed = 2.0 cm/hr d. Local Raisin speed = 2.0 cm/hr; Raisin 1 speed = 4.0 cm/hr; Raisin 3 speed = 6.0 cm/hr e. Local Raisin speed = 4.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 2.0 cm/hr

e. Local Raisin speed = 4.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 2.0 cm/hr

On the cosmic calendar, which compresses the history of the universe into a single year, about when did early humans first walk on Earth? a. in June b. in September c. in mid-December d. on December 30 e. just a few hours before midnight on December 31

e. just a few hours before midnight on December 31