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的边缘；它们只是会慢慢消失。

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

但是这星云或多或少更像个不成形的水滴。

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

猎户座星云是种特殊星云，叫做恒星摇篮。

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

看到了无数星团，明亮的星云，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的形状。

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

个正在诞生新恒星的恒星形成区域。

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

在其四张照片中，有两张展示了巨大的和尘埃云——也就是星云。

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

猎户剑的位置有猎户座星云，是种由尘埃、氢、氦及其组成的云。

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

这通常发生在云膨胀时，比如行星状星云或超新星。

Gas inside a nebula can be in turmoil, too.

星云内的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来，形成新的星云，即大团富含化学物质的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的片状、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的奇迹之。

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

在星云的中心处，这颗恒星的星核依然存在着，在引力的作用下它已是面目全非。

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

我们地球上的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.

行星状星云中的光芒是由中央炽热的白矮星激发产生的。

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的完整版本。

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

发现这实际上不是星云。

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

HAI 视频中的星云广告——所以每个城镇的时间都略有不同。