2. 外语
  3. As early as kindergarten we’ re taught that there are nine planets, but 200 years ago, even scholars were sure there were only s

As early as kindergarten we’ re taught that there are nine planets, but 200 years ago, even scholars were sure there were only s

admin2009-06-15  60
问题 As early as kindergarten we’ re taught that there are nine planets, but 200 years ago, even scholars were sure there were only six planets.
2.     As recently as the 1700s, people still believed that the planet Saturn was at the farthest extent of the solar system. That there might be other planet wasn’t even a respectable idea.
3.     In 1781 a self-taught astronomer, William Herschel, was "sweeping the skies" with his telescope. By March, he had reached the section including the constellation Gemini, and he spotted an object that appeared as a disk rather than a glowing star. Because it moved slightly from week to week, Herschel thought it was a comet. After a few mouths, however, he decided the orbit was circular’" and came to the shocking conclusion that it wasn’t a comet, but an unknown planet.
4.     People were astonished. No one since ancient times had anyone named a planet. Herschel felt that is should be called "Georgium Sirius" (George’s Star) after George Ⅲ, the king of England, some wanted to name it "Herschel" after its discoverer. But one influential astronomer suggested "Uranus", after the Greek god of the heavens. That made sense, since it was thought to be the limit of the solar system.
5.     Could there be another planet affecting Uranus? A century earlier, Isaac Newton had come up with laws describing the effects that the gravitational forces of planets have on one another.  Using Newton’s laws, two young scientists, Jean Leverrier and John Couch Adams set out independently in 1840 to find the unknown planet whose gravitational forces might be pulling on Uranus. Both hoped the unknown planet would be where their calculations said they could find it. Adams finished his calculations first, in September 1845. The following August, Leverrier completed his.
6.     Leverrier traveled to the Berlin Observatory in Germany, and the young assistant mana get, Johann Gottfried Galle, agreed to help search for the planet. That was September 23, 1846. That night, Galle looked through the telescope, calling out stars and their positions while a young student astronomer, Heinrich Louis d’ Arrest, looked at a star chart, searching for the stars Galle described. Finally Galle called out an eighth-magnitude star that d’ Arrest couldn’t locate on the charts. They had found the unknown planet! It had taken two years of research—but only a half hour at the telescope. The honor of the discovery belongs to both Adams and Leverrier, who had essentially discovered the new planet with just a pen and a new set of mathematical laws. The greenish planet was named after Neptune, god of the sea.
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答案D
解析 句意：天王星是由一位自学成才的天文学家发现的。
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