Assignment #1 (Chapter 1)

Read Chapter 1

1.) In your own words, write definitions for "solar system", "galaxy", and "cluster"

2.) What physical force gathers material into stars, galaxies, clusters, and superclusters?

3.) What physical process provides the energy that powers stars?

4.) The nearest star (Proxima Centauri) is 4.2 light years away.

• A. If we could communicate with creatures living on a planet orbiting Proxima Centauri, how long would it take for one of our messages to reach them?
• B. If Proxima Centauri blew up last night, what would we see in the sky when we look in its direction tonight (assume a clear night)?

5.) Compare the ages of the Earth, Sun, our galaxy (the Milky Way), and the Universe:

• A. The Earth is almost (i.e. within 80% of) the age of our galaxy
• B. The Earth is almost (i.e. within 80% of) the age of the Universe
• C. Our galaxy is almost (i.e. within 80% of) the age of the Sun
• D. Our galaxy is almost (i.e. within 80% of) the age of the Universe

6.) Which of these is true?

• A. The Sun has remained in approximately the same place in the galaxy since about 230,000,000 years after the galaxy formed
• B. The Sun has moved from the Andromeda galaxy into the Milky Way galaxy in the last 230,000,000 years
• C. The Sun makes an orbit around the center of the galaxy about once every 230,000,000 years
• D. None of the above

7.) When scientists say that the universe is expanding like a raisin cake, do they mean that (pick one):

• A. All distant galaxies are moving away from us at approximately the same velocity
• B. We can determine where the center of the universe is located by finding the center of the expansion
• C. All regions of the universe are expanding at approximately the same rate
• D. Distant galaxies are moving further and further apart, but the space is not expanding