In a lot of nebulae there's no sharp edge; they just kinda fade away.

在很多星云中并没有尖锐边缘；它们只是会慢慢消失。

However, this nebula started off more or less as a big shapeless blob.

但是一开始这星云或多或少更像个不成形水滴。

The orion nebula is a special kind of nebula called a stellar nursery.

猎户座星云是一种特殊星云，叫做恒星摇篮。

He saw clusters of stars, brightly colored nebulas, even entire galaxies!

他看到了无数星团，明亮星云，甚至还看到了整个银河！

That's a very common shape for planetary nebulae.

这是行星状星云很常见形状。

It is a nebula: a star-forming region where new stars are being born.

一个正在诞生新恒星恒星形成区域。

Among the other four images were two that showed huge clouds of gas and dust – called nebulas.

在其他四张照片中，有两张展示了气体和尘埃云——也就是星云。

Orion's sword is home to the great orion nebula, a cloud of dust, hydrogen, helium, and other gases.

猎户剑位置有猎户座星云，是一种由尘埃、氢气、氦气及其他气体组成云。

That usually happens when a gas cloud is expanding, like in a planetary nebula or supernova.

这通常发生在气体云膨胀时，比如行星状星云或超新星。

Gas inside a nebula can be in turmoil, too.

星云内气体也可能处于混乱状态。

Those elements will spread out to become a nebula, a rich chemical cloud drifting through space.

这些物质最后会扩散开来，形成新星云，即一团富含化学物质云团飘逸在宇宙之中。

These can create lovely sheets, tendrils, and filaments in nebulae as well.

这些也可以在星云中创造出可爱片状、卷须和丝状物。

The Orion nebula is one of the wonders of the universe.

猎户座星云是宇宙中奇迹之一。

At the centre of the nebula lies the remnant of the star, its core, crushed by the force of gravity.

在星云中心处，这颗恒星星核依然存在着，在引力作用下它已是面目全非。

Everything we find on the Earth today also originated in that nebula.

我们地球上一切也都来源于那片星云。

The glow in a planetary nebula is due to the hot central white dwarf exciting the gas.

行星状星云中光芒是由中央炽热白矮星激发气体产生。

And thus, only in three dimensions can a nebula or infant galaxy start out not flat and end up flat

因此，只有在三维空间才可能有星云或星系诞生时不是平面而最後变成平面。

You  can watch the full version of all these videos at nebula.

您可以在 nebula 上观看所有这些视频完整版本。

He discovered that this was not, in fact, a nebula.

他发现这实际上不是星云。

Nebula ads in HAI videos—so every town had a slightly different time.

HAI 视频中星云广告——所以每个城镇时间都略有不同。