The gap is due to one of Saturn's moons, Mimas.

这个缺口是由土星的卫星之一土卫一造成的。

I already mentioned Mimas, an icy moon that carves out the Cassini Division with its gravity.

我已经提到过土卫一，这是一颗通过自己的引力切割出卡西尼缝的冰冻卫星。

This is called a resonance, and it means that the particles at that location get tugged repeatedly by the gravity of Mimas, which in essence yanks them out of their orbit.

这被称为共振，意思是在那个位置的粒子会被土卫一的引力不断地拖拽，这实际上把它们拉出了自己的轨道。