土卫二

每一颗撞上土卫二的粒子就会产生好几个替代粒子，因此E环可以自给自足。

Each grain that hits Enceladus generates multiple replacement particles , so the E ring could be self-sustaining .

土卫二继续喷发冰粒到土星轨道中，使处于外围的E环充满了微小的微粒。

Enceladus continues to exhale water ice into Saturn orbit , keeping the E ring topped off with tiny particles .

科学家将此次研究结果刊登于《科学》（Science）杂志，称土卫二在一片18至24英里（29至39公里）厚的冰面下方存有液态水。

The scientists , who reported their work in Science , said the moon has a reservoir of water beneath a sheath of ice 18 to 24 miles thick .

然而，最近对土卫二喷射到土星E环中的冰所做的地面观测却恰恰相反，没有找到任何钠存在的证据。

Conversely however , recent Earth-based observations of ice ejected by Enceladus into Saturn 's E-Ring showed no evidence of the expected sodium .

NASA认为，夏威夷海岸附近的深海火山的周围环境，与土星的卫星土卫二很相似。

NASA believes the environment around a deep-sea volcano off the coast of Hawaii is similar to that of Saturn 's moon , Enceladus .

美国国家航空航天局（NationalAeronauticsandSpaceAdministration，NASA）的“卡西尼”（Cassini）号探测器对土卫二进行重力测量后发现了该片湖水，卡西尼号过去10年中穿越于土星的多颗行星之间。

The subsurface lake on the moon Enceladus was revealed by gravity measurements made by the National Aeronautics and Space Administration 's Cassini probe , which has been traveling among Saturn 's moons for the past decade .

美国和意大利行星科学家周四称，在土星的最小卫星之一土卫二（Enceladus）的一片冰面下方发现了大片液态水，其规模和地球上最大的湖相当。这是太阳系外围或适宜生命存在的又一证据。

Under an icy crust , one of Saturn 's smallest moons harbors a pool of water equal to the largest lakes on Earth , adding to evidence that the frigid outlands of the solar system may be suitable for the chemistry of life , planetary scientists in the U.S. and Italy said Thursday .

上面这幅高解析的土卫二影像，就是来自卡西尼号近距离飞越所摄；

Pictured above , a high resolution image of Enceladus is shown from a close flyby .

但土卫二还有个间歇泉，经常向太空喷射水汽和微小冰粒。

But Enceladus also has geysers that frequently vent water vapor and tiny ice grains into space .

在飞过土卫二的几年后，再回过头看，我们都大吃一惊。

and after a couple years looked back after it flew by Enceladus and surprised us all .

土卫二在向太阳系喷出一片片的水，再回落到它的表面。

Enceladus is blasting sheets of water out into the solar system and sloshing back down onto the moon .

最开始，土卫二存在水只是一个假设，但2015年发现的一些证据给科学家们带来了希望。

At first , the presence of water was simply a hypothesis after some evidence found in 2015 gave scientists hope .

在最近，分析卡西尼号捕获的土卫二尘埃物质，发现有钠的成份，暗指底层有个咸水的海洋。

Most recently , an analysis of dust captured by Cassini found evidence for sodium as expected in a deep salty ocean .

土卫二为何如此活跃还是个未解之谜，因为与土卫二毗邻、大小相近的土卫一似乎寂若死灰。

Why Enceladus is active remains a mystery , as the neighboring moon Mimas , approximately the same size , appears quite dead .

比如，土卫二和木卫二是太阳系中两颗冰封的卫星，表面温度是零下几百度。

Enceladus and Europa , for instance , are two icebound moons in the local solar system with surface temperatures hundreds of degrees below zero .

内圈卫星一般缺少这样的颜色，这是因为土卫二会喷出冰状的物质形成新的保护层。

The inner moons are largely devoid of such coloration , thanks to a fresh coat of icy material that spews out from the moon Enceladus .

2005年卡西尼号探测到土卫二南极地区附近的孔中喷射出水蒸气和冰，而这里正是冰下湖的所在处。

In 2005 , the Cassini probe detected water vapor and ice spewing from vents near the moon 's South Pole , where the subsurface lake is located .

研究人员表示，土卫二的海洋比土卫四更接近表面，特别是在冰壳只有数千米厚的南极地区。

Enceladus ' ocean , according to researchers , is likely much closer to the surface , particularly in the southern polar regions where the icy crust might be only a few kilometers thick .

和曾经在南极区域向太空喷射巨大水蒸汽流的土卫二不一样，土卫四相对“安静”，但是研究人员认为它的表面远古时期活动性更强。

Unlike Enceladus , which has geysers of water that spurt from the southern polar region , Dione appears " quiet " now , but researchers say it likely had a more active past .

当时卡西尼探测器观测到土卫二出现较大的前后振动，该现象叫做“天平动”，从而检测到了海洋。如果土卫二天平动幅度更小，那么这意味着其地壳更厚。

One way Enceladus ' ocean was discovered was by observing " large back-and-forth oscillations , called libration . " If the libration was smaller on the moon , it would likely mean the crust was thicker .

按照拥有的水量排序，从少到多依次是：土卫二，土卫四，地球，木卫二，冥王星，海卫一，木卫四，土卫六和木卫三。

In order of how much water they have , from the least to the most , they are : Enceladus , Dione , Earth , Europa , Pluto , Triton , Callisto , Titan , and Ganymede .

卡西尼号在研究土星的同时，还探索了可能存在外星生命的土卫六和土卫二。

While it studied the planet , Cassini explored moons - Titan and Enceladus - that could be home to extraterrestrial life .

在土星诸多的卫星中，和那充满碳氢化合物的兄弟土卫六不同，土卫二作为又一颗可能存在液态水的星球，引得整个天文界对它众说纷纭。

Enceladus , another of Saturn 's many moons , has the astronomy world abuzz with its potential to hold water , unlike its hydrocarbon-rich sister .