土星环系 Saturn's ring system 主要是由冰晶所组成的土星周围盘状物。已认出的土星环由内到外有 D (最暗弱)、C (黑纱环)、 B (最亮) 和 A (次亮) 环，A 环和 B 环间有道隙缝称为卡西尼环缝。
四月，绕土星运行的机器人卡西尼号土星探测器拍了这张横穿太阳系最有名的环的窄角照片。
In April, the robotic Cassini spacecraft now orbiting Saturn took this narrow-angle view looking across the Solar System's most famous rings.
这个太阳系中最大的光环的轨迹距离土星800万英里，比其他土星环远50倍。
The ring, the largest in the solar system, surrounds the planet from a distance of 8m miles, about 50 times further out than the others.
因为土星环几乎纯粹由水冰构成-而外太阳系的物质构成通常是冰岩混合物。
Because the rings are almost pure water ice-and material in the outer solar system is generally an ice-rock mix.
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