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Astronomers strip Pluto of its status as a planet天文学家取消冥王星行星地位

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发表于 2006-8-25 08:42 |只看该作者
With one vote, toys and models of the solar system became instantly obsolete, forcing teachers and publishers to scramble to update textbooks and lessons used in classrooms for decades.
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发表于 2006-8-25 08:43 |只看该作者
Discovered in 1930 by the American Clyde Tombaugh, the icy rock of Pluto has traditionally been considered the ninth planet, farthest from the sun in the solar system.
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发表于 2006-8-25 08:44 |只看该作者
However, the definition of a planet, approved after a heated debate among 2,500 scientists from the International Astronomical Union (IAU) meeting in Prague, drew a clear distinction between Pluto and the other eight planets.
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4#
发表于 2006-8-25 08:45 |只看该作者
The scientists agreed that, to be called a planet, a celestial body must be in orbit around a star while not itself being a star.
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发表于 2006-8-25 08:46 |只看该作者
It must be large enough in mass for its own gravity to pull it into a nearly spherical shape and have cleared the neighborhood around its orbit.
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发表于 2006-8-25 08:47 |只看该作者
Pluto was disqualified because its oblong orbit overlaps Neptune's. Xena also does not make the grade of being a planet, and will also be known as a dwarf planet.
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发表于 2006-8-25 08:49 |只看该作者
The agreed-upon definition -- the first time the IAU has tried to define scientifically what a planet is -- comes in sharp contrast to the draft sent around to delegates at the General Assembly last week.
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发表于 2006-8-25 08:51 |只看该作者
The new definition creates a second category called "dwarf planets," as well as a third category for all other objects, except satellites, known as small solar system bodies.
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发表于 2006-8-25 08:52 |只看该作者
From now on -- or 'at least for the time being' joked one delegate -- traditional planets will be restricted to eight: Mercury, Venus. Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
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10#
发表于 2006-8-25 08:53 |只看该作者
It's an issue mainly for the public, not really for scientists.
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11#
发表于 2006-8-25 08:56 |只看该作者
Officials at the American Museum of Natural History in New York had been at the vanguard of the movement to demote Pluto and were feeling vindicated on Thursday.
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12#
发表于 2006-8-25 09:01 |只看该作者
请冷玉将此贴移至书院
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13#
发表于 2006-8-25 09:07 |只看该作者
书院帖子可以慢慢浏览,潜心细读
聊作无益之事,以遣有涯之生

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14#
发表于 2006-8-25 09:11 |只看该作者
来自世界各地的天体物理学家在布拉格投票,取消冥王星的地球第九大行星资格,原因是它按照新的行星定义,不具备围绕一颗形体运转的独立的运行轨道(他与海王星的轨道交叉重叠,没有依靠自身的质量形成绕太阳旋转的独立轨道),而且其直径很小,质量不大
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15#
发表于 2006-8-25 09:13 |只看该作者
这样,太阳系便只剩下八大行星。课本和科普文章都得重新修订。从小知道太阳系有九大行星的我们也必须改变观念了
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