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的花朵，一撮星云是无数天体的蚁聚。

You can see nebulae in the clear summer sky.

在晴朗的夏夜可以看到天上的星云。

Extragalactic nebula is invisible to the naked eye.

用肉眼是看不到河外星系的。

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.

的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的物质块。这叫做原恒星。