So, what would such a planet need?

　　Student: Water?

　　Professor: Yes, it need to be the right temperature to sustain liquid water.

　　Student: And it would need to be a rocky planet, I mean, as opposed to a gas giant.

　　Professor: Ok, good. An earth-like planet. Now, as to that, there are some recently detected exoplanets that might actually be earth-like.

　　For example, there’s a red dwarf star, that’s what most stars are, um...that’s called Gliese 581.

　　Gliese 581 is...well, it’s a lot more interesting than that name makes it seem.

　　This host star is considered a near neighbor of our solar system because it’s only about 20 light years away.

　　It’s pretty close by astronomical standards, and being a red dwarf star, it’s small and relatively cool, at least compared with the Sun.

　　And researchers have discovered planets orbiting Gliese 581.

　　These exoplanets have been named, ready? Gliese 581 B, C, D, E, in alphabetical order of their discovery.

　　那么，那種星球需要什么呢?

　　學(xué)生：水?

　　教授：是的，它需要有合適的溫度來維持液態(tài)的水。

　　學(xué)生：而它需要是一個(gè)多巖石的星球，我的意思是，與一個(gè)由氣體組成的龐然大物截然相反。

　　教授：是的，很好。也就是一個(gè)類地行星。關(guān)于這一點(diǎn)，有一些最近探測到的外星星球也許真的是類地行星。

　　比如說，有一個(gè)紅色的矮星，大部分恒星都是矮星，它被叫做Gliese 581。

　　Gliese 581是......它比它的名字聽起來可有趣多了。

　　這個(gè)寄主星被認(rèn)為是我們太陽系的一個(gè)近鄰，因?yàn)樗�離太陽系只有20光年的距離。

　　按照天文學(xué)標(biāo)準(zhǔn)來看非常近了，而且作為一個(gè)紅色的矮星，它體積很小，相對較涼爽，至少和太陽相比是這樣。

　　而且研究人員發(fā)現(xiàn)了環(huán)繞Gliese 581運(yùn)行的行星。

　　這些外星星球被命名為......你們準(zhǔn)備好了嗎?它們被按照發(fā)現(xiàn)順序以字母順序命名，分別是Gliese 581 B, C, D, E。