The gas glows, and we call this an emission nebula.

气体会发光，我们称之为发射星云。

This is an emission nebula located just below Orion's belt.

这是位于猎户座星带下方的发射星云。

The color of an emission nebula depends on the gas in it and how hot it is.

发射星云的颜色取决于其中的气体和它的温度。

Not too far from the Orion Nebula in the sky is another dark nebula, superposed on a bright emission nebula.

天空中离猎户座星云不远的地方是另一个暗星云，它叠加在一个明亮的发射星云上。