When that happens, you get that idealized soap bubble nebula.

如此一来，就会得到理想的肥皂泡星云。

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.

但是一开始这星云或多或少更像个不形的水滴。

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，明的星云，甚至还看到了整个银河！

But sometimes nebulae do have sharp edges.

但有时星云确实有锋利的边缘。

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.

一个正在诞生新恒星的恒星形。

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，有两张展示了巨大的气体和尘埃云——也就是星云。

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

猎户剑的位置有猎户座星云，是一种由尘埃、氢气、氦气及其他气体组的云。

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，形新的星云，即一大团富含化学物质的云团飘逸在宇宙之中。

So planetary nebulae really may owe their existence to planets!

所以行星状星云的存在可能真的要归功于行星！

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.

星云内的气体也可能处于混乱状态。

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

猎户座星云是宇宙中的奇迹之一。

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。

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.

我们上的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.

行星状星云中的光芒是由中央炽热的白矮星激发气体产生的。

Stars, nebulae, stellar clusters of various sorts, the occasional supernova.

恒星、星云、各种类型的星团，偶尔还有超新星。