Yesterday, I wrote about the magnificent Hubble mosaic of the nearby galaxy M33, aka the Triangulum Galaxy. This face-on spiral is an understated wonder, faint by eye, but close enough that Hubble reveals treasures.
One of the jewels inside it is NGC 604, which I described briefly in the article. I didn't go into much detail on this nebula for two reasons: One is that it wasn't the main thrust of the article and I didn't want to wander off too much, and the other is that the nebula looks weird in the image — only two filters were used to create the released image, and so the nebula appears vividly blue. But... the nebula is most certainly not blue.