NASA科學家發現715顆新行星

National Aeronautics and Space Administration scientists announced Wednesday the discovery of 715 new planets around distant stars, including four alien worlds roughly the size of Earth that might be the proper temperature for liquid water to form and, therefore, potentially suitable for life.

美國國家航空航天局(National Aeronautics and Space Administration，簡稱NASA)週三宣佈，發現了715顆圍繞遙遠恆星運行的新行星，其中包括四顆與地球大小差不多的新行星。這四顆行星或許擁有適合液態水形成的溫度，因此可能適宜生命存在。

This latest discovery, based on two years of data collected from 150,000 or so stars by the agency's orbiting Kepler space telescope, brings the confirmed count of planets outside our solar system to nearly 1,700 worlds.

這一最新發現以NASA開普勒太空望遠鏡用兩年時間從大約15萬顆恆星收集到的數據爲基礎。至此，太陽系外人類確切知道的行星數量增至近1,700個。

'We have alMost doubled the number of planets known to humanity,' said planetary scientist Jack Lissauer at NASA's Ames Research Center in Mountain View, Calif., who is a science co-investigator on the $600 million Kepler space telescope mission.

美國加州山景城(Mountain View)NASA艾姆斯研究中心(Ames Research Center)的行星科學家利斯奧爾(Jack Lissauer)說，人類已知的行星數量幾乎增加了一倍。他是耗資6億美元的開普勒太空望遠鏡任務的科學聯合研究員。

The team of three dozen astronomers, data analysts and planetary scientists detailed their findings in two research papers submitted to the Astrophysical Journal and discussed their findings Wednesday during a press conference held by NASA.

這個由36個宇航員、數據分析師和行星科學家組成的小組在兩篇研究論文中詳述了他們的發現，並在週三NASA舉行的新聞發佈會上討論了其成果。論文已提交給《天體物理學雜誌》(Astrophysical Journal)。

Almost all of these newly verified exoplanets--as the alien worlds are called--are smaller than the planet Neptune, a gaseous giant at the outer reaches of our solar system that is almost four times the size of Earth. The worlds are clustered around just 305 stars in solar systems that, like our own, contain multiple planets, the scientists said.

所有這些剛被證實的系外行星都比海王星要小。海王星是運行在太陽系外層空間的一個巨大的氣態行星，體積是地球的近四倍。科學家說，這些行星分別圍繞恆星系內的305顆恆星運行。那些恆星系跟我們的太陽系一樣，內有多個行星。

The researchers said that four of these newly confirmed planets are less than 2.5 times the size of Earth and orbit in the so-called habitable zone around their stars--that is, the distance at which the surface temperature of an orbiting planet may be right for liquid water. That means it would be not so hot that it would boil into space and not so cold that it would freeze solid.

研究人員說，在這些新確認的行星中，有四顆行星的體積還不到地球的2.5倍，其軌道處於恆星周圍的宜居帶。行星若與恆星保持這樣的距離，說明該行星的表面溫度可能適合液態水的生成，也就意味着這一溫度不至於高到液態水蒸發，也不至於低到凍結爲固態。

One of those new planets, called Kepler-296f, is twice the size of Earth and orbits a star half the size and only 5% as bright as our sun, said Jason Rowe, a research scientist at the SETI Institute and a member of the Kepler science group.

外星生命探尋研究所(SETI Institute)研究員、開普勒科學組的成員羅伊(Jason Rowe)說，在那些新發現的行星中有一顆被命名爲“Kepler -296f”，體積是地球的兩倍，圍繞一顆只有太陽一半大小且亮度只有太陽5%的恆星運轉。

Details of the others--designated Kepler 174d, Kepler 298d and Kepler 309c--weren't publicly available Wednesday. The total, though, 'increases the number of Earth-sized planets by 400%,' Mr. Rowe said.

那些被命名爲Kepler 174d、Kepler 298d和Kepler 309c的行星的具體情況週三沒有對外公開。不過羅伊說，發現了這些行星後，人類已知的與地球同等大小的行星數量增加了四倍。

Taken together, the new Kepler discoveries confirm that 'small planets are extremely common in our galaxy,' said planetary physicist Sara Seager at the Massachusetts Institute of Technology, who wasn't involved in the discoveries. 'I am extremely excited about this.'

麻省理工學院(Massachusetts Institute of Technology)地球物理學家西格爾(Sara Seager)說，開普勒望遠鏡的新發現證實，小行星在銀河系極爲普遍，對此我感覺十分興奮。他沒有參與發現新行星的任務。

The data were collected before the Kepler telescope malfunctioned last year, leaving it unable to track stars precisely enough to continue the planet-hunting mission for which it was launched in 2009. The Kepler scientists are now seeking funding from NASA to operate the telescope for another two years, in a reduced role, to study how planets form around stars.

這些數據是在開普勒望遠鏡去年發生故障之前收集的。出現故障後，該望遠鏡無法足夠準確地追蹤這些行星，也就無法繼續2009年啓動的行星搜索任務。開普勒科學家目前正努力從NASA那裏尋求資金，從而能再使用兩年開普勒望遠鏡，這次該望遠鏡將扮演一個次要角色，主要研究行星如何在恆星周圍形成。

In the meantime, the researchers continue to pore through data collected while it was still working properly. Several thousand possible planet candidates exist, of which scientists expect to be able to confirm several hundred more planets in orbit around other stars.

在開普勒望遠鏡仍正常工作期間，研究人員繼續整理收集來的數據。目前存在着數千個可能的行星候選者，科學家希望能從這些候選者中確認，還有幾百個運行在其它恆星周圍軌道上的行星。