Name: __________________________  Date: _____________

1.	In the Hubble classification scheme for spiral galaxies, the tightness of the winding of the spiral arms appears to be related directly to	
A)	the age of the galaxy, as determined from the age of its individual stars.	
B)	the number of globular clusters in the halo of the galaxy.	
C)	the overall intrinsic size of the galaxy, or the diameter across the spiral arms.	
D)	the size of the central bulge of the galaxy.	

2.	The typical diameter of a spiral galaxy is about	
A)	107 ly.	
B)	105 ly.	
C)	1 ly.	
D)	100 ly.	

3.	What mechanism is believed to produce flocculent spiral galaxies?	
A)	Satellite galaxies plunging through the disk of the nuclear spiral galaxy	
B)	Self-propagating star formation, where star formation occurs in bursts	
C)	Shock waves from explosive star formation in the nuclear bulge	
D)	Density waves in the interstellar medium	

4.	What mechanism is believed to produce grand-design spiral galaxies?	
A)	Shock waves from explosive star formation in the nuclear bulge	
B)	Density waves in the interstellar medium	
C)	Satellite galaxies plunging through the disk of the nuclear spiral galaxy	
D)	Self-propagating star formation, where star formation occurs in bursts	

5.	What is the designation given to a galaxy with a large nuclear bulge and tightly wound arms starting from a bar through the nuclear bulge?	
A)	Sb	
B)	SBa	
C)	SBc	
D)	Sa	

6.	How do most spiral galaxies rotate?	
A)	The arms lead as the galaxy rotates (arms point forward).	
B)	Spiral galaxies do not rotate; if they did, then the spiral pattern would soon disappear.	
C)	We do not know; they rotate far too slowly for us to have seen any motion in the time since galaxies were discovered.	
D)	The arms trail as the galaxy rotates (arms point backward).	

7.	What is an elliptical galaxy?	
A)	A galaxy with an elliptical outline and a smooth distribution of brightness with no structure apparent in the galaxy	
B)	A spiral galaxy seen from an angle, giving it an elliptical profile	
C)	Any galaxy with an elliptical halo when observed at radio wavelengths	
D)	A spiral galaxy with an elliptically shaped nuclear bulge and the spiral arms starting from the ends of the ellipse	

8.	In which category of galaxy do we find the largest galaxies in the universe?	
A)	Lenticular galaxies	
B)	Large spiral galaxies like the Milky Way	
C)	Irregular galaxies	
D)	Elliptical galaxies	

9.	Which of the following types of galaxies contains primarily population II, metal-poor, low-mass, long-lived stars?	
A)	Elliptical galaxies	
B)	Barred spiral galaxies	
C)	Starburst galaxies	
D)	Flocculent spiral galaxies	

10.	An astronomer studying a cluster of galaxies finds a galaxy that is round and has a disk and central bulge like a spiral galaxy, but has no spiral arms. How should the astronomer classify this galaxy?	
A)	E0	
B)	E7	
C)	Sa	
D)	S0	

11.	The overall distribution of galaxies through space is now found to have	
A)	galaxies distributed uniformly throughout space, out to the farthest distances.	
B)	galaxies clustered together in several high-density centers with very little matter linking them together.	
C)	galaxies concentrated around one position in space, presumably the original site of the Big Bang.	
D)	galaxies concentrated on the surface of huge open spaces or voids, like soap bubbles.	

12.	A supercluster of galaxies is	
A)	a cluster of galaxy clusters.	
B)	a cluster of galaxies that is packed much more densely than normal clusters, giving it a higher mass.	
C)	a phrase describing all the galaxies in the universe as a single system.	
D)	a cluster of galaxies that is spread out over a larger than normal volume of space.	

13.	What is the Local Group?	
A)	The stars that occupy the same spiral arm as the Sun	
B)	A cluster of about 40 galaxies of which the Milky Way is a member	
C)	A group of galaxies clustered around the Andromeda Galaxy M31, apparently gravitationally bound to it but separate from the Milky Way	
D)	A group of about 100 stars within 20 ly of the Sun that appear to have been formed at about the same time from similar material	

14.	What is a rich cluster of galaxies?	
A)	A cluster with more spiral galaxies than ellipticals	
B)	A cluster (like our Local Group) that contains at least two large galaxies	
C)	A cluster with a high metal content	
D)	A cluster containing thousands of galaxies	

15.	What is a poor cluster of galaxies?	
A)	A cluster with very few spiral galaxies compared to other types	
B)	A cluster with very little gas or dust	
C)	A cluster with a low metal content	
D)	A cluster containing a few dozen galaxies	

16.	A rich, regular cluster of galaxies differs from a rich, irregular cluster in that it	
A)	has its galaxies distributed in a regular, highly flattened system (like a disk).	
B)	contains fewer galaxies than an irregular cluster.	
C)	lacks the giant elliptical galaxies often found in irregular clusters.	
D)	has fewer spirals and more ellipticals and S0 galaxies than an irregular cluster.	

17.	Collisions between galaxies	
A)	occur only very occasionally to produce spectacular supergalaxies with many new stars within them. Only one or two examples have been detected so far.	
B)	are occurring all the time, all elliptical galaxies having resulted from such collisions. These collisions have cleared out all the gas and dust from these galaxies.	
C)	never happen since galaxies are so far apart in our universe.	
D)	can and do occur relatively frequently over cosmological times.	

18.	What is believed to be the origin of starburst galaxies?	
A)	The galaxies are slower rotators than other galaxies, so the slower-speed collisions between interstellar clouds produce more star formation.	
B)	The galaxies are newly formed and are undergoing their initial, rapid star formation.	
C)	A recent collision with another galaxy has triggered a wave of star formation.	
D)	A recent series of supernovae has compressed the interstellar medium and started a wave of star formation.	

19.	What is believed to be the origin of giant elliptical galaxies?	
A)	They formed that way and have remained unchanged ever since.	
B)	They grew by devouring smaller galaxies.	
C)	Collisions of galaxies in the cluster produces a smooth distribution of stars through the cluster, which sink to the center of the cluster and form giant galaxies there.	
D)	They have grown continuously since their formation by accretion of intergalactic gas.	

20.	Which one of the following statements is true about clusters of galaxies?	
A)	The observed mass of the galaxies of the cluster is many thousands of times too small to hold the cluster together.	
B)	The observed mass of the galaxies of the cluster is about 10 times larger than the amount needed to hold the cluster together.	
C)	The observed visible mass of the galaxies in the cluster is about 10 times too small to hold the cluster together.	
D)	The observed mass of the galaxies of the cluster is almost exactly equal to that needed to hold the cluster together.	

21.	Many rich, regular clusters of galaxies contain substantial amounts of very hot, intergalactic gas. What is believed to have produced this hot gas?	
A)	Collisions between galaxies in the cluster	
B)	Bursts of star formation in merging galaxies	
C)	Supernovae (exploding stars)	
D)	Jets of gas ejected by supermassive black holes at the centers of the galaxies	

22.	The Hubble law indicates that	
A)	the Milky Way Galaxy appears to be at or near the center of the known universe.	
B)	all nearby galaxies are moving toward us and all far away galaxies are moving away from us.	
C)	the farther galaxies are receding faster than the nearby galaxies.	
D)	the universe will expand forever.	

23.	Which of the following speeds are described by Hubble's law?	
A)	The speeds of individual galaxies in the Local Group and other nearby galaxy clusters	
B)	The speeds of superclusters of galaxies	
C)	The speeds of stars in our own Galaxy	
D)	The speeds of individual clusters of galaxies in our own local supercluster	

24.	“Standard candles,” which are important for finding distances to remote galaxies, are	
A)	stars and other objects of known intrinsic brightness.	
B)	standard laboratory light sources with which the brightness of a galaxy can be compared.	
C)	standard bars of known length with which the size of a galaxy can be measured.	
D)	heat sources used for calibrating infrared observations of galaxies.	

25.	What is the brightest “standard candle” found so far, and therefore the one that is visible to the greatest distance?	
A)	Type Ia supernovae	
B)	The brightest H II regions in each galaxy	
C)	The brightest globular cluster of each galaxy	
D)	Cepheid variables	

26.	What is the Tully-Fisher relation?	
A)	The more distant the galaxy, the greater the recessional velocity.	
B)	The brighter the Cepheid, the longer the pulsation period.	
C)	The more distant the galaxy, the fainter it appears.	
D)	The brighter the galaxy, the wider the 21-cm radio emission line.	

27.	The following distance-measuring techniques, arranged in order of the distance for which they are most effective, from smallest to greatest, are	
A)	Cepheid variables, spectroscopic parallax, Type Ia supernovae, and Tully-Fisher relation.	
B)	spectroscopic parallax, Tully-Fisher relation, Cepheid variables, and Type Ia supernovae.	
C)	spectroscopic parallax, Cepheid variables, Tully-Fisher relation, and Type Ia supernovae.	
D)	Cepheid variables, spectroscopic variables, Type Ia supernovae, and Tully-Fisher relation.	

Answer Key

1.	D	
2.	B	
3.	B	
4.	B	
5.	B	
6.	D	
7.	A	
8.	D	
9.	A	
10.	D	
11.	D	
12.	A	
13.	B	
14.	D	
15.	D	
16.	D	
17.	D	
18.	C	
19.	B	
20.	C	
21.	A	
22.	C	
23.	B	
24.	A	
25.	A	
26.	D	
27.	C