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The Discovery of Astronomers The discovery of planets ar

游客2024-10-15  9
问题                     The Discovery of Astronomers
    The discovery of planets around distant stars has become like space-shuttle launches—newsworthy but just barely. With some 50 extrasolar planets under their belt, astronomers have to announce something reafly strange to get anyone’s attention.
    Last week they did just that. Standing in front of colleagues and reporters at the American Astronomical Society’s semiannual meeting in San Diego, the world’s premier planet-hunting team—astronomer Geoffrey Marcy of the University of California, Berkeley, and his colleagues—presented not one but two remarkable finds. The first is a pair of planets, each about the mass of Jupiter, that whirl around their home star 15 light-years from Earth in perfect lockstep. One takes 30 days to complete an orbit, the other exactly twice as long. Nobody has ever seen such a configuration. But the second discovery is far stranger—a solar system 123 light-years away, in the constellation Serpens, that harbors one " ordinary" planet and another so huge—17 times as massive as Jupiter—that nobody can quitefigure out what it can be. It is, says Marcy, "a bit frightening. "
    What’s frightening is that these discoveries make it clear how little astronomers know about planets and they add to the dawning realization that our solar system— and by implication Planet Earth may be a cosmic oddball. For years theorists figured that other stars would have planets more or less like the ones going around the sun. But starting with the 1995 discovery of the first extrasolar planet—a gassy monster like Jupiter but orbiting seven times as close to its star as Mercury orbits around our sun— each new find has seemed stranger than the last. Searchers have found more "hot Jupi-ters" like that first discovery. These include huge planets that career around their stars not in circular orbits but in elongated ones; their gravity would send any Earthlike neighbors flying off into space. Says Princeton astronomer Scott Tremaine: "Not a single prediction for what we’d find in other systems has turned out to be correct."
    Last week’s giant was the most unexpected discovery yet. Conventional theory suggests that it must have formed like a star, from a collapsing cloud of interstellar gas. Its smaller companion, only-seven times Jupiter’s mass, is almost certainly a planet, formed by the buildup of gas and dust left over from a star’s formation.
    Yet the fact that these two orbs are so close together suggests to some theorists that they must have formed together—so maybe the bigger one is a planet after all.
    Or maybe astronomers will have to rethink their definition of "planet." Just because we put heavenly objects into categories doesn’t mean the distinctions are necessarily valid. And as Tremaine puts it, "When your classification schemes start breaking down, you know you’re learning something exciting. This is wonderful stuff." [br] The two finds are remarkable in that______.
选项 A、the planets are far from our solar system
B、the sizes of the plants are too huge
C、astronomers have never seen similar orbiting pattern and size before
D、scientists cannot figure out what they can be
答案 C
解析 事实细节题。文中第二段指出第一个发现里的两颗行星的运行轨道排列方式前所未见，第二个发现里面有一颗是木星体积17倍的巨大星体。其他各项在原因方面都罗列得过于简单，只有[C]把这两点都包括了，所以是正确答案。
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