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托福阅读背景知识:彗星(comet)

作者: share 发表于: 2016-11-30 17:54
天文学是托福阅读考试中经常涉及的科目,也是困扰文科生的难题。本文美联出国考试专门向同学们介绍大家普遍觉得比较 “难” 的天文学的相关基础知识。本文是第一篇:彗星。

天文学是托福阅读考试中经常涉及的科目,也是困扰文科生的难题。本文美联出国考试专门向同学们介绍大家普遍觉得比较 “难” 的天文学的相关基础知识。本文是第一篇:彗星(comet)。

A comet is an icy small Solar System body that, when passing close to the Sun, heats up and begins to outgas, displaying a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind upon the nucleus of the comet. Comet nuclei range from a few hundred metres to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. The coma and tail are much larger and, if sufficiently bright, may be seen from the Earth without the aid of a telescope. Comets have been observed and recorded since ancient times by many cultures.

​彗星是太阳系中的小型含冰天体。当其接近太阳时,温度上升,释放气体,(彗星)大气层或者彗发清晰可见,有时还会产生彗尾。这些现象中是由太阳辐射和太阳风作用于彗核引起的。彗核直径从数百米到几十公里不等,由冰、尘埃及小岩石颗粒等松散混合物组成。彗发和彗尾要比彗核大,如果彗发、彗尾亮度足够,在地球上可以不用借助望眼镜就能看到它们。彗星自古就在许多文化中有观测和记载记录。

托福阅读背景知识:彗星(comet)

Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several millions of years.

​彗星通常有偏心椭圆形轨道,不同的彗星有不同的公转周期,从几年到大约数百万年不等。

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