土星，特提斯，光环和阴影
(原标题: Saturn, Tethys, Rings, and Shadows)
2022-01-23
浏览次数: 17
从冰卫星特提斯上看，光环和阴影将展示土星系统的奇妙景象。最近没去过特提斯吗？那么卡西尼号宇宙飞船拍摄的这幅华丽的环景现在就只能这样了。2005年，在照片中央左下方的阳光下，特提斯本身的直径约为1000公里，轨道距离这颗气态巨行星的中心不到5个土星半径。在这个距离上（大约30万公里），它远在土星明亮的主环之外，但特提斯仍然是在暗淡而脆弱的外E环边界内的五个主要卫星之一。在20世纪80年代发现的两颗非常小的卫星Telesto和Calypso被锁定在特提斯的轨道上。忒勒斯托在前面，卡吕普索在特提斯后面，三颗行星环绕土星。
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Seen from ice moon Tethys, rings and shadows would display fantastic views of the Saturnian system. Haven't dropped in on Tethys lately? Then this gorgeous ringscape from the Cassini spacecraft will have to do for now. Caught in sunlight just below and left of picture center in 2005, Tethys itself is about 1,000 kilometers in diameter and orbits not quite five saturn-radii from the center of the gas giant planet. At that distance (around 300,000 kilometers) it is well outside Saturn's main bright rings, but Tethys is still one of five major moons that find themselves within the boundaries of the faint and tenuous outer E ring. Discovered in the 1980s, two very small moons Telesto and Calypso are locked in stable along Tethys' orbit. Telesto precedes and Calypso follows Tethys as the trio circles Saturn.