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2018年雅思听力材料:新行星的发现

888真人赌博   2018-04-19   【

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文章摘要:2018年雅思听力材料:新行星的发现,因此,要想在网络安全的国际话语权问题上取得突破,一方面需要上合组织坚持自身理念,吸引更多发展中国家的支持;另一方面也需要在仔细甄别后适当吸收其他网络安全理念中的合理成分。伴随高温超高压机组、超高温超高压机组快速普及,企业自发电水平逐年提高。  也门外交部当天发表声明说,不能将荷台达港口从整个荷台达市分离出来单独考虑,胡塞武装必须从荷台达市全部撤出。,由于未涉及所有种族和区域的艺术作品,却把自己叫做全球展,有记者事前评论这个双年展是一个后殖民主义的教学现场。  曾几何时,国产电影总是上一部赚到了钱,才会计划下一部跟进,导致前后作品缺乏创作逻辑上的内在关联,充满盲动性,甚至热衷于自我颠覆,今年春节档上映的《捉妖记2》之所以让人失望,部分原因即在于此。(草案第十一条第三款、第十九条)  五、关于选举的组织和程序  选举法规定:“全国人民代表大会常务委员会主持全国人民代表大会代表的选举。。

2018年雅思听力材料:新行星的发现

  If three's a crowd, a new planet recently discovered orbiting a sunlike star is really cluttering up its neighborhood.

  The new planet is the fourth Jupiter-like world to be found around the young star HR 8799, astronomers announced today. The same team had previously found the other three planets in 2008, when they took a direct picture of the star system.

  Of the more than 500 planets discovered to date outside our solar system, most have been found via indirect methods, such as looking for planets' gravitational tugs on their host stars or for dips in starlight when planets pass in front of their hosts.

  The new planet was also found in a direct image of the HR 8799 system. But based on the masses of the planets and their distances from the star, the fourth world challenges current theories of planet formation, according to the study authors.

  "This is the first multiplanet system directly imaged so far, so it's quite a feat," said lead study author Christian Marois, an astronomer at the Herzberg Institute of Astrophysics in Canada.

  "But we are now stuck with four planets [and] we cannot explain their formation and their current locations by any of our models."

  Fourth Planet Too Close to Its Parent?

  The previously known planets around HR 8799 are about five, seven, and ten times Jupiter's mass. They orbit between 2.2 billion miles (3.5 billion kilometers) from the star—roughly the same as Neptune's distance from the sun—and 6.3 billion miles (10.1 billion kilometers), or almost twice Pluto's distance.

  The most distant planet circles just inside a dusty disk similar to that produced by the solar system's Kuiper belt, a region of small, icy bodies that includes Pluto.

  The whole HR 8799 system is estimated to be no more than 60 million years old, so the planets are still glowing with heat from their formation. This heat signature is what betrayed the planets' positions in the previous infrared images of the star.

  Astronomers found the fourth planet using the Keck II telescope on the peak of Mauna Kea in Hawaii. The instrument is equipped with a special near-infrared imager and adaptive optics to eliminate the blurring effect of Earth's atmosphere.

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