Milky Way Galaxy Guided Reading

2. 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

b. Galileo Galilei

13. 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?

b. Orion Spur

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

b. While the dark matter cannot be observed with our present-day instruments, we still have a pretty good idea what it consist of

11. You suddenly get an uncontrollable urge to find out more about the other side of the Milky Way Galaxy (the regions beyond the center). Where should you rush off to?

b. a radio telescope that can observe at 21-cm wavelengths

3. What objects did Harlow Shapley use as "signposts" to figure out the extent of the Milky Way Galaxy and the location of its center?

b. globular clusters

25. 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?

b. in a globular cluster high above the Galaxy's disk

22. 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?

b. the Hubble Space Telescope has shown us a visible-light image of an accretion disk at

10. Our Milky Way Galaxy is what type of galaxy?

A spiral

5. 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?

c. a CD or DVD

21. 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?

c. about 17 times the size of the Sun

26. 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?

c. because the SMC is small and its stars are widely spaced, the rate of star formation (and star death) is much slower there

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

c. in the disk

23. Astronomers believe that the center of our Galaxy has a black hole with enough mass inside to make almost 4 million Suns! How do astronomers think a black hole could acquire so much mass?

c. the center of our Galaxy is a much more crowded region than where the Sun is found; we still see material falling toward the center and material has fallen in for billions of years

1. 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?

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

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

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

16. How do astronomers measure the mass that the Galaxy contains inside the orbit of the Sun?

c. they measure the distance to the center of the Galaxy and the period of the Sun's orbit and then use Kepler's Third Law

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

d. a cloud of gas or star that is further from the center will generally take more time to orbit

7. 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

d. a set of huge clouds with many interesting molecules (like alcohol, carbon monoxide, and ammonia) in them

31. 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?

d. all of the above

30. What was especially noteworthy about the Sagittarius Dwarf Galaxy when it was discovered among the small galaxies near the Milky Way?

d. it was on a collision course with the Milky Way and would be swallowed by it eventually

8. Which of the following statements about the nuclear bulge of our Galaxy is FALSE?

d. the best way to learn more about it is to observe higher energy radiation, such as ultraviolet and x-rays

14. A "galactic year" as defined by astronomers is:

d. the time it takes the Sun to revolve once around the center of the Milky Way Galaxy

17. 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?

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

4. What have we learned from the work of Harlow Shapley and others about the location of the Sun in the Milky Way Galaxy?

d. we are in the disk of the Galaxy, about 3/5 of the way from the center

19. 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")?

e. a new kind of subatomic particle

27. The Population I stars in the Milky Way Galaxy

e. all of the above

9. An astronomer needs to measure the distance to a globular cluster of stars that is part of the Milky Way Galaxy. What method should she try to use to find the distance?

e. find a variable star (cepheid or RR Lyrae) in the cluster

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

e. the observation of long moving streams of stars that continue to orbit through our Galaxy's halo

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

a. Sagittarius A

6. The central region of our Galaxy is not as flat as its main disk of stars. Which of the following has roughly the same shape as our central region of stars?

a. a peanut

12. 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?

a. measuring the Doppler shift of a line in a radio spectrum