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        地球水來源 彗星是關鍵
        文章來源:未知 文章作者:enread 發布時間:2019-05-27 08:22 字體: [ ]  進入論壇
        Scientists proposed a new theory about the origin of oceans on Earth.
        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 observatory1 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 Infrared2 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 atmospheric3 water allowed the telescope to accurately4 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 neutron5 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 coma6 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.


        1 observatory hRgzP     
        • Guy's house was close to the observatory.蓋伊的房子離天文臺很近。
        • Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文臺的職員們每天對大鐘檢查兩次。
        2 infrared dx0yp     
        • Infrared is widely used in industry and medical science.紅外線廣泛應用于工業和醫學科學。
        • Infrared radiation has wavelengths longer than those of visible light.紅外輻射的波長比可見光的波長長。
        3 atmospheric 6eayR     
        • Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面溫度與大氣環流是密切相關的。
        • Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通過大氣窗區向地表輻射能量。
        4 accurately oJHyf     
        • It is hard to hit the ball accurately.準確地擊中球很難。
        • Now scientists can forecast the weather accurately.現在科學家們能準確地預報天氣。
        5 neutron neutron     
        • Neutron is neutral and slightly heavier than the proton.中子是中性的,比質子略重。
        • Based on the neutron energy,the value of weighting factor was given.根據中子能量給出了相應的輻射權重因子的數值。
        6 coma vqxzR     
        • The patient rallied from the coma.病人從昏迷中蘇醒過來。
        • She went into a coma after swallowing a whole bottle of sleeping pills.她吃了一整瓶安眠藥后就昏迷過去了。
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        TAG標簽: water comet earth