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　　When Geoff Marcy was 14, his parents bought him a telescope．Every night, he would go onto the roof outside his window to see the wonders of the sky．

　　“What excited me most was whether there were planets in other solar systems where life might exist,”he says．“I decided to try to find planets orbiting(沿…轨道运行)other stars like our Sun．”

　　And he did．“My fellow researcher, Paul Butler, and I found our first planet in 1995,”Dr．Marcy says．“We worked for ten years without finding anything!But we stuck with it, and our patience paid off．”

　　Since then, the two scientists have discovered 65 of the more than 100 planets orbiting other stars．Dr．Marcy and Dr．Butler also spotted the first“family”of three planets．In June 2002 they announced another discovery：a Jupiter-like(像木星一样的)planet orbiting star 55 Cancri．

　　At first, the two researchers found only planets that orbit close to stars．Recently, the scientists found planets farther out．The planet orbiting 55 Cancri is a major breakthrough：it is the first sighting of a large gas planet about the same distance from the star as Jupiter is from the Sun．

　　Why is this important?Scientists think that life on Earth may exist because of two special features in our solar system．The first is Jupiter．

　　“Because it’s so big, Jupiter pulls comets and asteroids(小行星), or they all come and hit the Earth．”Dr．Marcy explains．“Without Jupiter, life on Earth would likely have been destroyed．”

　　A second feature is that Earth is a rocky planet where liquid water, which is necessary for life, can exist．Unlike gas planets, rocky planets like Earth have surfaces where water can gather in pools and seas, which may support life．A huge space exists between the Jupiter-like planet and two other planets that lie close to 55 Cancri．Is there an Earthlike planet in the space, too small for us to notice?If so, says Dr．Marcy,“We would have two striking similarities to our solar system：a Jupiter-like planet and an Earth-like planet．And there may be life!”

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