单词：cometary nebula
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This is Scientific Americans 60-Second Science. Im Karen Hopkin. This will just take a minute. If youve ever wondered where the Earth came from, the answer, it seems, is blowin in the windthe solar wind. Or so say scientists who, after examining sola
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反射星云是靠反射附近恒星的光线而发光的，呈蓝色。反射星云的光度较暗弱，较容易观测到的例子是围绕着金牛座M45七姊妹星团的反射星云，在透明度高及无月的晚上，利用望远镜便可看到
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The Aeneid by Virgil 《埃涅阿斯纪》维吉尔 Mark first read the Aeneid while he was studying Latin in high school, and he recountedthe story of Aeneass quest and his desire to build a city that, he said, quoting the text in English, knows no
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The Aeneid by Virgil 《埃涅阿斯纪》维吉尔 Mark first read the Aeneid while he was studying Latin in high school, and he recounted the story of Aeneass quest and his desire to build a city that, he said, quoting the text in English, knows no
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How old is the Earth? 地球的年龄有多大？ Well, by counting the number of isotopes in a sample of rock that's undergone radioactive decay, 通过对岩石样品中正经历着放射衰变的同位素计数， geologists have estimated the Ear
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It looks like a hand of God reaching out into the cosmos, but NASA says the display is caused by a young and powerful pulsar. Taken by NASA's Chandra X-ray observatory from it's orbiting 360 miles above the Earth, the recently released photo of Pulsa
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