这个颜色表明与余下的其他星云比起来，温度相对比较低，密度也相对较大。

This color indicates that they are relatively cool and dense, compared to the rest of the gas in the nebula.

youdao

这个颜色表明与余下的其他星云比起来，温度相对比较低，密度也相对较大。

This color indicates that they are relatively cool and dense, compared to the rest of the gas in the nebula.

youdao