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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,由于家庭贫困,樊桂英一生未读过书,而这也是她一生最大的遗憾。因为,互联网对社会生产、生活的改造无所不在。在军事应用体系方面,美军将人工智能应用推向整个军事领域的方方面面。,  有观点指出,这样的遣返数据与加拿大去年审结的一批移民造假案不无相关:  2016年10月28日,王洵等4名华裔无牌移民顾问被指在上千宗中国人移民加拿大申请文件中,造假来骗取永久居留权和公民身份,所涉罪名包括蓄意误导、伪造文书、税务造假等12项控罪。2016年6月,浙江省特色小镇规划建设工作联席会议办公室组织考核时,经浙江省省政府审定,有3个小镇被警告,1个被降格为省级特色小镇培育对象,首现“落榜生”。编辑:张斯航。

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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