A bit of mould is a pleiad of flowers;a nebula is an ant-hill of stars.

一粒霉菌是一簇美不胜收花朵，一撮星云是无数天体蚁聚。

You can see nebulae in the clear summer sky.

在晴朗夏夜可以看到天上星云。

Extragalactic nebula is invisible to the naked eye.

们用肉眼是看不到河外星系。

As our nebula began to collapse under its own gravity and spin faster, a dense clump of matter formed in the center. It's called a protostar.

们星云在自身重力作用下崩溃和更加快速地旋转时，星云中心形成了密集物质块。这叫做原恒星。