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。
2
The theory neatly accounts for why Saturn's rings are nearly pure ice, while most objects in that part of the solar system are more an ice-rock blend.
这一理论严谨地解释了为什么太阳系中这一部分的大多数物体都是冰岩混合物，而土星的光环却近乎都是冰块。
3
The icy rings of Saturn could be what's left of an ancient ice-rock moon that got stripped and swallowed by the gas-giant planet. Christopher Intagliata reports.