双语阅读英语外刊精讲:太阳系迎来首个星际访客(附音频)

2019-03-04 14:31:10来源:酷学英语

  “For decades we've theorized that such interstellar objects are out there, and now – for the first time – we have direct evidence they exist,” said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate in Washington. “This history-making discovery is opening a new window to study formation of solar systems beyond our own.”

  Immediately after its discovery, telescopes around the world, including ESO's Very Large Telescope in Chile and other observatories around the world were called into action to measure the object's orbit, brightness and color. Urgency for viewing from ground-based telescopes was vital to get the best data.

  Combining the images from the FORS instrument on the ESO telescope using four different filters with those of other large telescopes, a team of astronomers led by Karen Meech of the Institute for Astronomy in Hawaii found that 'Oumuamua varies in brightness by a factor of ten as it spins on its axis every 7.3 hours. No known asteroid or comet from our solar system varies so widely in brightness, with such a large ratio between length and width. The most elongated objects we have seen to date are no more than three times longer than they are wide.

  “This unusually big variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape,” said Meech. We also found that it had a reddish color, similar to objects in the outer solar system, and confirmed that it is completely inert, without the faintest hint of dust around it.”

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