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地球大小的新行星被发现

Not too big, not too small. Not too hot, not too cold. A newly discovered planet looks just right for life as we know it, according to an international group of astronomers¹.

不太大又不太小，不太冷又不太热。一个国际天文组织说，一个最新被发现的星球看起来正适合我们所知的生命存在条件。

Orbiting a star about 500 light-years away, the planet called Kepler-186f is about the same size as Earth. As this artist’s interpretation² shows, it orbits its star at the right distance for liquid water on the surface. That is an essential condition for life as we know it.

这颗名叫开普勒-186f的行星围绕一个恒星运行，距地球500光年，跟地球差不多大。就像天文学家解释的，它围绕它的恒星运行，距离正好可以使行星表面有液态水。我们知道，这是生命存在的基本条件。

But it is not exactly like Earth, NASA planetary scientist Elisa Quintana said via Skype.

但是美国航空航天局行星科学家昆塔纳通过网络电话说，它与地球并不完全相同。

“It’s more of an Earth’s cousin. It’s not an Earth’s twin. It shares the same characteristics as Earth, but their parent stars are very different," said Quintana.

美国航空航天局行星科学家昆塔纳说：“它更像是地球的表兄妹，而不是孪生兄妹。它与地球有共同特征，但是它们的母恒星是非常不一样的。”

Kepler-186f orbits a star that is smaller and cooler than our sun.

开普勒-186f围绕的恒星比太阳小，温度比太阳低。

But, writing in the journal Science, the astronomers say the planet appears to be a closer relative than most of the hundreds of others discovered so far.

但是，天文学家在科学杂志上写道，与之前发现的数百颗星球的大多数相比，这颗行星与地球更相似。

Some are massive gas-covered giants with thick, crushing atmospheres. Others orbit too closely to their stars and are too hot for life.

有些星球是由厚厚气体覆盖的巨型体，另一些离它们围绕的恒星太近，因为温度太高，无法让生命存在。

Two planets discovered last year are in the right orbit and might be good candidates for life, Quintana says, but they are a bit bigger than Earth.

去年发现的两颗行星运行轨道适中，或许可以作为生命生存地的备选，但是它们比地球大了一点。

“For the first time, we can actually say we now have a planet that is both Earth-sized and orbits in its star’s habitable zone," she said.

昆塔纳说：“这是第一次我们能够说我们现在有一个星球，不仅与地球一样大，而且是围绕恒星周围距离适中的宜居带运行。”

It may be the first time, but it probably is not the last, says Massachusetts Institute of Technology astrophysicist Sara Seager.  She spoke³ to VOA via Skype.

麻省理工学院天体物理学家西格说，这或许是第一次，但很可能不是最后一次。

“We’ve been waiting decades to understand how common habitable planets might be, and it’s looking like they’re really common. And this gives us excitement and motivation to take the next step," said Seager.

麻省理工学院天体物理学家西格说：“多少年了，我们一直想知道宜居行星可能有多少共同之处，看起来，它们的确很相似。这让我们很兴奋，也使我们有动力采取下一步行动。”

The next step would be to look for traces of life in the atmospheres of these distant worlds. That would take a more sophisticated space telescope. But budget cuts threaten that mission, says University of California at Los Angeles astrophysicist Ben in this Skype interview.

下一步就是在这些遥远世界的大气层里寻找生命迹象。这需要一个更复杂的天文望远镜。但加州大学洛杉矶分校天体物理学家朱克曼在网络电话访谈中说，预算削减使这一使命难以完成。

“In principle, we could do this in the next couple decades.  But in practice, because there’s no money, it’s not gonna happen. It’s not gonna happen in my lifetime, for example," said Zuckerman.

加州大学洛杉矶分校天体物理学家朱克曼说：“原则上说，我们能在接下来的20年中做这件事。但是实际上，因为缺少资金，我们没法做。比如说，在我有生之年是做不到了。”

Leaving earthbound concerns behind, NASA’s Elisa Quintana believes that when the next-generation space telescope is launched, it will find that we are not alone in the universe.

抛开对地球上各种问题的担忧，美国航空航天局的昆塔纳相信，下一代天文望远镜问世后，它会发现宇宙中还有其他生命存在。

“I guess I’m an optimist⁴. I think that life is definitely out there. Just looking at the abundance of stars. I mean, hundreds of billions of stars. The likelihood that one of them might have some form of life to me seems rather high. But everyone has their own opinion about that, I’m sure," she said.

昆塔纳说：“我猜我是个乐观主义者。我认为地球之外一定有生命存在。看，宇宙中有那么多星球。我是说，数千亿星球。我认为其中一个或许存在生命的可能性看起来相当高。当然，我肯定每个人对这个问题都有自己的观点。”

In the meantime, the search continues for other worlds where life may find a home.

同时，对可能适合生命生存的其他世界的搜寻仍在继续。