They're called Ganymede, Callisto, and Europa.

这几个分别叫木卫、木卫四和木卫二。

The next biggest moon is Callisto, at 4800 km in diameter.

第二大卫星是木卫四（卡利斯托），直径约4800公里。

That means the surface is very old, maybe as old as Callisto itself.

这意味着它的表面非常，能和木卫四同岁。

Callisto orbits Jupiter farthest out of the four biggies, almost two million km away.

在四个大行星中，木卫四的公转轨离木星最远，约达200万千米。

Juice will investigate three of the so-called Galilean moons-Callisto, Europa and Ganymede, all of which are thought to have subsurface oceans.

“果汁”探测器将调查所谓的伽利略卫星——木卫四、木卫二和木卫，这卫星都被认为拥有地下海洋。

The four largest moons, Io, Europa, Ganymede, and Callisto, are large enough to be seen from Earth with a telescope.

从地球上就以用望远镜看到最大的四卫星，木卫一，木卫二，木卫，木卫四。

In 1610, for example, Galileo used the first telescope to discover Jupiter's moons Io, Callisto, Europa, and Ganymede — now known as the Galilean Moons.

例如，1610 年，伽利略用第一台望远镜发现了木星的卫星木卫一、木卫四、木卫二和木卫，这些卫星现在被称为伽利略卫星。

" Jupiter's biggest moon is Ganymede, not Callisto, " she said, pointing over Ron's shoulder at a line in his Astronomy essay, " and it's lo that's got the volcanoes."

“木星最大的卫星是木卫，不是木卫四，”她从罗恩身后指着他那篇天文学论文中的一行文字说，“有火山的应该是木卫一。”

The ESA took the opportunity to do a test run of Juice's instruments, which it will use to look for molecular signatures of habitability on the moons Europa, Ganymede and Callisto.

欧洲航天局借此机会对 Juice 的仪器进行了测试，这些仪器将用于寻找木卫二、木卫和木卫四上适宜居住的分子特征。