National Aeronautics¹ 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.

美国国家航空航天局(National Aeronautics and Space Administration，简称NASA)周三宣布，发现了715颗围绕遥远恒星运行的新行星，其中包括四颗与地球大小差不多的新行星。这四颗行星或许拥有适合液态水形成的温度，因此可能适宜生命存在。

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.

这一最新发现以NASA开普勒太空望远镜用两年时间从大约15万颗恒星收集到的数据为基础。至此，太阳系外人类确切知道的行星数量增至近1,700个。

'We have almost doubled the number of planets known to humanity,' said planetary scientist Jack² 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.

美国加州山景城(Mountain View)NASA艾姆斯研究中心(Ames Research Center)的行星科学家利斯奥尔(Jack Lissauer)说，人类已知的行星数量几乎增加了一倍。他是耗资6亿美元的开普勒太空望远镜任务的科学联合研究员。

The team of three dozen astronomers³, data analysts⁴ and planetary scientists detailed⁵ their findings in two research papers submitted to the Astrophysical Journal and discussed their findings Wednesday during a press conference held by NASA.

这个由36个宇航员、数据分析师和行星科学家组成的小组在两篇研究论文中详述了他们的发现，并在周三NASA举行的新闻发布会上讨论了其成果。论文已提交给《天体物理学杂志》(Astrophysical Journal)。

Almost all of these newly verified exoplanets--as the alien worlds are called--are smaller than the planet Neptune⁶, a gaseous⁷ 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.

所有这些刚被证实的系外行星都比海王星要小。海王星是运行在太阳系外层空间的一个巨大的气态行星，体积是地球的近四倍。科学家说，这些行星分别围绕恒星系内的305颗恒星运行。那些恒星系跟我们的太阳系一样，内有多个行星。

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.

研究人员说，在这些新确认的行星中，有四颗行星的体积还不到地球的2.5倍，其轨道处于恒星周围的宜居带。行星若与恒星保持这样的距离，说明该行星的表面温度可能适合液态水的生成，也就意味着这一温度不至于高到液态水蒸发，也不至于低到冻结为固态。

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.

外星生命探寻研究所(SETI Institute)研究员、开普勒科学组的成员罗伊(Jason Rowe)说，在那些新发现的行星中有一颗被命名为“Kepler -296f”，体积是地球的两倍，围绕一颗只有太阳一半大小且亮度只有太阳5%的恒星运转。

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.

那些被命名为Kepler 174d、Kepler 298d和Kepler 309c的行星的具体情况周三没有对外公开。不过罗伊说，发现了这些行星后，人类已知的与地球同等大小的行星数量增加了四倍。

Taken together, the new Kepler discoveries confirm that 'small planets are extremely common in our galaxy,' said planetary physicist⁸ Sara Seager at the Massachusetts Institute of Technology, who wasn't involved in the discoveries. 'I am extremely excited about this.'

麻省理工学院(Massachusetts Institute of Technology)地球物理学家西格尔(Sara Seager)说，开普勒望远镜的新发现证实，小行星在银河系极为普遍，对此我感觉十分兴奋。他没有参与发现新行星的任务。

The data were collected before the Kepler telescope malfunctioned⁹ last year, leaving it unable to track stars precisely¹⁰ 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.

这些数据是在开普勒望远镜去年发生故障之前收集的。出现故障后，该望远镜无法足够准确地追踪这些行星，也就无法继续2009年启动的行星搜索任务。开普勒科学家目前正努力从NASA那里寻求资金，从而能再使用两年开普勒望远镜，这次该望远镜将扮演一个次要角色，主要研究行星如何在恒星周围形成。

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.

在开普勒望远镜仍正常工作期间，研究人员继续整理收集来的数据。目前存在着数千个可能的行星候选者，科学家希望能从这些候选者中确认，还有几百个运行在其它恒星周围轨道上的行星。