Extragalactic nebula is invisible to the naked eye.

们用肉眼是看不到河外星系的。

You can see nebulae in the clear summer sky.

在晴朗的夏夜可以看到天上的星云。

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。

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。

Extragalactic nebula is invisible to the naked eye.

我们用肉眼是看不到河外系的。

You can see nebulae in the clear summer sky.

在晴朗的夏夜可以看到天上的。

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，一撮是无数天体的蚁聚。

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.

当我们的在自身重力作用下崩溃和更加快速地旋转时，中心形成了密集的物质块。这叫做原恒。

Extragalactic nebula is invisible to the naked eye.

我们用肉眼是不外星的。

You can see nebulae in the clear summer sky.

在晴朗的夏夜可天上的星云。

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。

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.

当我们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。

Extragalactic nebula is invisible to the naked eye.

我们用肉眼是看不到河外系的。

You can see nebulae in the clear summer sky.

在晴朗的夏夜可以看到天上的。

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

粒霉菌是簇美不胜收的花朵，撮是无数天体的蚁聚。

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.

当我们的在自身重力作用下崩溃和更加快速地旋转时，中心形成了密集的物质块。这叫做原恒。

Extragalactic nebula is invisible to the naked eye.

我们用肉眼是看不到河外系。

You can see nebulae in the clear summer sky.

在晴朗夏夜可以看到天上。

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，一撮是无数天体蚁聚。

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.

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

Extragalactic nebula is invisible to the naked eye.

我们用肉眼是看到河外星系的。

You can see nebulae in the clear summer sky.

在晴朗的夏夜可以看到天上的星云。

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

一粒霉菌是一胜收的花朵，一撮星云是无数天体的蚁聚。

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.

当我们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。

Extragalactic nebula is invisible to the naked eye.

我们用肉眼看不到河外星系的。

You can see nebulae in the clear summer sky.

在晴朗的夏夜可以看到天上的星云。

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

一粒一簇美不胜收的花朵，一撮星云无数天体的蚁聚。

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.

当我们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。

Extragalactic nebula is invisible to the naked eye.

我们用肉眼是看不到河外星。

You can see nebulae in the clear summer sky.

晴朗夏夜可以看到天上星云。

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。

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.

当我们星云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。

Extragalactic nebula is invisible to the naked eye.

我们用肉眼到河外系的。

You can see nebulae in the clear summer sky.

在晴朗的夏夜可以到天上的云。

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

一粒霉菌一簇美胜收的花朵，一撮云无数天体的蚁聚。

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.

当我们的云在自身重力作用下崩溃和更加快速地旋转时，云中心形成了密集的物质块。这叫做原恒。

Extragalactic nebula is invisible to the naked eye.

我们用肉眼是看不到外星系。

You can see nebulae in the clear summer sky.

在晴朗以看到天上星云。

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。

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.

当我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。