This has led astronomers to become interested in oceans.

這讓天文學家對於海洋產生興趣。

And to the discovery that oceans can be very different to those beneath the open skies of Earth.

而了解到海洋深處與地球廣闊無垠的天空是如此地不同。

On three of the moons of Jupiter,

在木星的其中三個衛星，

and two of the moons of Saturn,

和土星的其中兩個衛星，

there was good evidence of liquid oceans.

都有液態海洋的明確證據。

The first of these oceans to be discovered was within Jupiter's moon Europa.

這些海洋中第一個被發現的是木星的衛星 Europa 上。

Though Europa is small, it may boast more liquid water than the Earth.

儘管 Europa 是顆小星體，它也許擁有比地球還更多的液態水。

The ocean could be over 100 kilometers deep.

海洋可能在超過 100 公里深處。

Heat generated by Jupiter's powerful tides keeps it warm underneath the icy shell.

因木星引起的強力潮汐產生的熱保持它地底下冰層溫暖。

Europe's Jupiter Icy Moons Explorer mission, or JUICE, will launch in 2022 to study Jupiter and three of its largest moons.

歐洲木星衛星冰層探索任務 (JUICE)，將會在 2022 年展開研究木星及其最大的三個衛星。

Perhaps one of the most promising oceans for study is on Enceladus, a tiny moon of Saturn.

也許其中一個最有希望找到海洋的研究目標是 Enceladus，土星的一個微小的衛星。

This is because the ocean does not stay under the ice cap.

因為它的海洋就不會存在於冰帽之下，

Geysers at the moon's south pole shoot ocean water hundreds of kilometers out into space.

在這個衛星的南極點的 Geysers 將海洋噴到外太空好幾百公里之處。

Studies by NASA's Cassini probe showed that

NASA 的 Cassini 探測器研究顯示，

the water in these jets contain organic molecules,

這些噴流的水中含有有幾分子，

the building blocks of life.

也就是有生命組成的基本元素。

There is also evidence of hydrothermal vents at the bottom of the ocean.

也有證據顯示在海洋底部有熱液排放的出口。

This is significant because it is thought that life first arose at hydrothermal vents on Earth.

這是非常了不起的，因為這被視為地球上的生命首先是從這些熱液出口中生成的。

A spacecraft flying through the jets of Enceladus

一艘太空船從 Enceladus 的噴流中飛過，

could sample the water for traces of complex

能夠採取水中複雜的生問分子樣本

biological molecules such as DNA or protein.

例如蛋白質或者 DNA。

There is no guarantee of life in the waters of Enceladus.

但不保證能夠在 Enceladus 的水體中

Or in any of the solar system's other hidden oceans.

或者在太陽系中其他任何的掩藏的海洋中找到生命的跡象。

But the possibility that something might be there will drive ambitious explorations for decades to come.

但是對於可能有生命在其中的微小可能性就足以驅動一些野心勃勃的探索計劃持續幾十年的時間。

Coming up, how to discover new planets.

接下來，要談談如何探索新的行星。