We live in one, the Milky Way, a gigantic disk galaxy with sprawling spiral arms.

我们就生活在其中一个之中——银河系，它是一个巨大的圆盘星系，有着伸展的旋臂。

Today you learned the Milky Way is a disk galaxy, a collection of dust, gas, and hundreds of billions of stars, with the Sun located about halfway out from the center.

今天你学到了银河系是一个盘状星系，由尘埃、气体和数千亿颗恒星组成，太阳位于离中心一半远的地方。