(单词翻译:单击)
Do you think there's life on other planets Don?
你认为其他行星上会有生命存在吗？
It seems perfectly reasonable that there would be Yael.
似乎完全有理由相信有生命存在。
what with how unfathomably largethe universe is.Don't you think？
宇宙如此之大，深不可测，不是吗？
I do.But then again, life is a tricky thing.
的确如此。但是话又说回来，生命的存在是一件极其有难度的事。
So much has to fall into place for the conditions for life aswe know it to be possible.
据我们所知，生命存在的可能性需要满足众多适合生存的条件。
For instance, a planet has to be just the right distance from the star itrevolves around.
比如说，行星与其所围绕旋转的恒星之间的距离是否适当。
How is that?
这有什么关系？
If it's too close to its star, the heat from the star would cause any water on the planet to boil away.
如果太近，来自恒星的热量会导致行星上水分蒸发，
If it's too far away, the opposite problem occurs:the cold temperature would cause water to freeze.
与之相反，要是距离太远，温度太低会致使水冻结。
The range of distance from a star that will allow water to remain a liquid is called the habitable zone.
与恒星之间的距离要能保持水呈现的是液体状态，这个范围被称作适居带。
So we Earthlings are lucky I guess that we are just the right distance away from the sun.
那我们地球岂不是很幸运，与太阳之间的距离正当适宜。
Very lucky it seems.
是非常的幸运。
In 2007, scientists discovered the first two Earth-like planets outside our solarsystem that appear to be located near or within their star's habitable zone.
2007年，科学家们在太阳系以外首次发现两颗类似地球，可能位于适居带附近的行星，
Previously discovered planets have had masses more akin to Jupiter's.
而之前发现的行星更类似于木星。
The planets orbit the same star andare known as Gliese 581c and Gliese 581d.
这两颗行星都围绕格利泽581恒星转动，因此他们被称作格利泽581d和格利泽581c。
Wow,so there is other life out there?
哇！那探索到有生命存在吗？
Not so fast, upon further investigation, it seems that Gliese 581d may be the only one of the two actually in the habitable zone, and its orbit seems to take it in and out of the zone.
没那么快。据进一步调查研究发现，格利泽581d可能是二者中在适居区以内的行星，而且其运行轨道使其在适居区内游离。
Not tomention as I said, a lot of factors must come into play for life to exist.
更何况正如我所说的，生命存在还有诸多因素要考虑，
Being within the habitable zone is just one of them.
在适居区只是其中之一。
