地球水来源 彗星是关键
文章来源:未知 文章作者:enread 发布时间:2019-05-27 08:22 字体: [ ] 
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Scientists proposed a new theory about the origin of oceans on Earth.
 
科学家就地球上海洋的来源提出了一项新理论。
 
They suggested that comets played a key role in delivering the life-enabling water to our planet billions of years ago.
 
The study published in the latest journal Astronomy and Astrophysics Letters showed that water in many comets may share a common origin with Earth's oceans.
 
The world's largest airborne 1 SOFIA operated by the U.S. space agency NASA found that Comet Wirtanen, as it made its closest approach to Earth in December of 2018, contains "ocean-like" water.
 
SOFIA, the Stratospheric Observatory for 2 Astronomy, is a Boeing 747 jetliner modified to carry a 2.7-meter diameter telescope, according to NASA.
 
Observing at high altitudes above much of the Earth's 3 water allowed the telescope to 4 measure the ratio of regular to heavy water in Comet Wirtanen. The regular water is H2O, while the heavy water is called HDO, which has an extra neutrally-charged particle called a 5 inside one of the hydrogen atoms.
 
The data showed that Comet Wirtanen's water ratio is the same as the Earth's oceans, according to the study.
 
Comparing the new data with previous studies of comets, the scientists found the ratio of regular to heavy water was not linked to the origin of the comets, for example, whether they were from the Kuiper Belt or the outer fringe of the solar system.
 
Instead, the ratio was related to how much water was released from ice grains in the comet's 6 compared to directly from the snowy surface, implying that all comets could have a heavy-to-regular water ratio similar to Earth's oceans.
 
If comets have the same ratio of these water types as Earth's oceans, it indicates that the water in both may share a common origin, according to the researchers.


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1 hRgzP     
n.天文台,气象台,瞭望台,观测台
参考例句:
  • Guy's house was close to the observatory.盖伊的房子离天文台很近。
  • Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。
2 dx0yp     
adj./n.红外线(的)
参考例句:
  • Infrared is widely used in industry and medical science.红外线广泛应用于工业和医学科学。
  • Infrared radiation has wavelengths longer than those of visible light.红外辐射的波长比可见光的波长长。
3 6eayR     
adj.大气的,空气的;大气层的;大气所引起的
参考例句:
  • Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
  • Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。
4 oJHyf     
adv.准确地,精确地
参考例句:
  • It is hard to hit the ball accurately.准确地击中球很难。
  • Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。
5 neutron     
n.中子
参考例句:
  • Neutron is neutral and slightly heavier than the proton.中子是中性的,比质子略重。
  • Based on the neutron energy,the value of weighting factor was given.根据中子能量给出了相应的辐射权重因子的数值。
6 vqxzR     
n.昏迷,昏迷状态
参考例句:
  • The patient rallied from the coma.病人从昏迷中苏醒过来。
  • She went into a coma after swallowing a whole bottle of sleeping pills.她吃了一整瓶安眠药后就昏迷过去了。
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