土卫四

9月28日，研究人员报告称，土星的一颗小卫星土卫四很可能也拥有一片次表层海洋。

On September 28 , researchers reported that Dione - a small moon of Saturn - probably has a subsurface ocean , too .

研究人员认为，土卫四的海洋自卫星形成以来就存在了，这为微生物提供了的宜居环境。

Dione 's ocean has likely been there since the moon formed , researchers said , adding that it could be host to microbial life .

研究人员认为，土卫四表层之下100千米处的这一巨大海洋深度足有数十千米，周围包裹着岩石。

Researchers say Dione 's ocean is likely 100 kilometers beneath the surface , " several tens of kilometers deep " and surrounds a rocky core .

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 .

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 .

比利时皇家天文台的研究人员表示，卡西尼探测器的最新引力数据表明，和土卫六以及土卫二一样，土卫四的表面之下也有一个巨大海洋。

Using gravity data from the Cassini probe , researchers at the Royal Observatory of Belgium say Dione joins Titan and Enceladus as Saturn moons likely having subsurface oceans .