听力原文：M: Doctor 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 planet 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. 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. Umm, 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. By doing this, they hope to learn about the chemical composition of these planets. Oxygen and ozone molecules, for example, would be the signs of life on these planets.
M: I'm looking forward to heating more when the telescope is in operation and I'm sure our readers would be interested too.
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A. The possible existence of life on other planets.
B. Methods for building powerful new telescopes.
C. A technical problem that astronomers can't solve.
D. The discovery of planets orbiting distant stars.