3.How does the professor organize types of encounters between galaxies?
A. From the quickest encounters to the slowest
B. From the most distant encounters to those closest to Earth
C. From the most frequent types of encounters to the least frequent
D.From the most violent types of encounters to the least violent
5. Why do astronomers believe that the Milky Way galaxy is interacting with another nearby galaxy?
A. Star formation has increased in both galaxies.
B. The two galaxies are slowly moving toward each other
C. A stream of gas and dust connects the two galaxies
D. The Hubble Space Telescope found high levels of hydrogen gas near the two galaxies
6. What is the professor’s opinion of recent observations of the Antennae galaxies?
A. It is too early to know if they will produce important findings
B. They are of limited value, as they only capture one stage in a long process
C. They illustrate the professor s point that there are multiple forms of galaxy encounters.
D. They are consistent with a commonly accepted scientific theory