A、By studying distortions of the light frequency of their parent stars. B、By observing their planets through telescope. C、By com

M:[22]Dr. Cole, thank you for agreeing to this interview for the Daily Campus News. Can you tell us about what you and your colleagues discussed at the annual astronomy society meeting last month?
W: Yes. For the first time ever, the scientific community has established the existence of planets outside our own solar system. Of course, we knew that certain distant stars existed, but only recently did we learn that several of them are orbited by their own planets.
M: Why did it take so long to locate those planets?
W: Well, you have to understand, that they are a billion times dimmer than their parent stars. It would be like trying to see the light of a candle next to a huge explosion. We don’t currently have a telescope that can be used to see them.
M: But if the astronomers didn’t see the planets through a telescope, how did they find them?
W: By a very indirect method. Hum, the astronomers measured subtle distortions in the frequency of the light from the parent stars and observed that some of the stars seem to rock back and forth. They determined that this is caused by the gravitational pull from orbiting planets.
M: There is a powerful new telescope being built in Arizona. Will that help them see these planets?
W: They should be able to see them at least in the form of small spots of light. And then the scientists would be able to break down and analyze this light.[25]By doing this, they hope to learn about the chemical composition of these planets. Oxygen and ozone molecules, for example, would be evidence of life on these planets.
22. What does the man probably do?
23. Why was it hard to locate the newly found planets?
24. How did the scientists establish the existence of the planets?
25. What can scientists learn by analyzing the light from the planets?