土星环

狠打；猛冲伽利略在400年前就指出了土星环的存在。

Galileo first spotted Saturn 's rings 400 years ago .

到1988年，我们将会看到土星环最壮丽的景象。

In 1988 we will be able to see Saturn 's rings in their fullest glory .

从后院的望远镜观察这些土星环是一种不错的选择。

Spotting these rings from a backyard telescope is a treat .

土星环所投的影子。清晰可见土星环到大气中氨的阴霾。

Clearly visible shadows cast by Saturn 's rings dense clouds of ammonia to the atmosphere .

有许多坑和斑纹的土卫五漂浮在远方，正从土星环外面的阴暗部分窥视着。

Crater-scarred Rhea floats in the distance , peeking out from behind Saturn 's partly shadowed rings .

因为土星环几乎是由纯冰构成，而外太阳系的物质基本上是冰岩混合体。

Because the rings are almost pure water ice & and material in the outer solar system is generally an ice-rock mix .

因为土星环几乎全部都是纯水，而在通常情况下，在太阳系外层会以冰-岩石混合物的形式存在。

Because the rings are almost pure water ice - and material in the outer solar system is generally an ice-rock mix .

优雅的土星环是区域性范例，但并不是唯一；太阳系的所有巨行星都有环。

Saturn 's rings are a graceful local example , but not the only one ; all the giant planets in our solar system have rings .

有一种理论认为，一颗巨大的小行星撞击地球的力量很大，导致岩石和碎片像进入土星环一样的环绕地球的轨道。

One theory is that a huge asteroid struck earth with such force that rock and debris were shot into orbit around the planet like the rings of Saturn .

然而，在距地球36000公里的轨道上物体绕转地球一周的时间为24小时，这个物体飞行时持续面对的是地球上的不变的同一个点，这样许多地球同步卫星的运行会形成一个类似的土星环。

Many , though , form a ring like Saturn 's at a distance of 36000km , the place at which an object takes 24 hours to orbit the Earth and thus hovers continuously over the same point of the planet .

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 .

它们的特殊之处在于拥有和土星外环一样的环带，20世纪50年代美国的一部UFO电影就曾以此作为素材。

What makes these two so special is the fact that they seem to have copied the rings of Saturn themselves , taking on a form that is straight out of a 1950s UFO B movie .

土星的环被照亮了很多，以至于发现了新的光环，虽然它们在上图中很难被看到。

Saturn 's rings light up so much that new rings were discovered , although they are hard to see in the image .

潘恩也叫“牧羊人卫星”，得名于“牧羊之神”。阿特拉斯得名于“双肩顶天”的太阳神提坦，这是因为它看起来像是在支撑土星的外环。

Pan , being what is known as a " shepherd moon , " got its name from the god of shepherds , while Atlas was named after the titan who " held the sky on his shoulders , " since it supports the rings of Saturn .

2009年，我们发现了土星的巨大外环，它是宇宙中已知最大的、延伸得最远的环，该环与主环成27度，分布在距土星表面128倍半径到207倍半径之间。

In 2009 , we discovered an enormous ring around Saturn , the farthest and largest band around the ringed world . The ring is tilted 27 degrees from the main rings and starts roughly 128 times the planet 's radius from its surface , extending to 207 times its radius into space .

自2004年抵达土星以来，卡西尼号宇宙飞船已经将土星、土星环及土星卫星的图片传送回地球。

The Cassini spacecraft has been sending home images of Saturn , its rings and its moons since arriving at the gas giant in 2004 .