Asking an astronomer what their favorite object is can be grossly unfair. It’s a big sky, with a lot of stuff in it — and you can quote me on that. We have thousands of gorgeous images of individual objects, and lots more that are interesting without having jaw-droppingly spectacular gorgeous images of them. 

But if you wake me up out of a cold sleep and ask me, I might just say NGC 604.

It’s a nebula, a star-forming gas cloud. We see lots of those, and honestly it’s hard to find one that isn’t really beautiful. This one has a lot of interesting structure to it, and a lot of stars are forming in the center. We can say that about a lot of other nebulae, too. So what makes NGC 604 special?

Well, it’s kinda big. And bright. And oh yeah it’s in another galaxy, and also so mind-stompingly luminous that it’s far and away the single brightest object in that galaxy, and in fact one of the largest and brightest nebulae within 10 million light-years.

So, yeah.

And, of course, when you have an object like that and you take a peek at it with JWST, what you get is beauty enough to torch a person’s soul.

Holy WOW.

NGC 604 is in M33, a nearby spiral also called the Triangulum Galaxy. M33 is the third biggest galaxy in our neighborhood (called the Local Group); our Milky Way and the Andromeda Galaxy are bigger. It’s very roughly 2.7 million light-years away, close enough to see by binoculars from a dark site. It’s face-on to us, so its light is spread out over a large area, making it appear dimmer, so it doesn’t get as much attention as Andromeda.

But then, Andromeda doesn’t have NGC 604.

The nebula is a freaking beast, roughly 1,500 light-years wide. If you put the Orion Nebula next to it you wouldn’t even notice it; Orion is about 25 light-years across. Heck, NGC 604 is so big it would actually stretch from here to the Orion Nebula, with gas to spare. Thousands of stars are forming in it, including hundreds of massive stars that are blasting out radiation; their combined radiation is well over one hundred million times the luminosity of the Sun, and they are providing the energy to light up this immense cloud. 

I’m thinking it’s good NGC 604 is in a different galaxy. If it were as close as Orion, it would outshine Venus in the sky. Much closer and it might actually be dangerous.

The image above, taken using the NIRCam (Near Infrared Camera) on JWST is a combination of six different infrared filters. What’s shown as blue is from long chains of carbon molecules called PAHs, for polycyclic aromatic compounds; essentially soot. Confusingly, along with teeny rocky grains, astronomers call this material dust. Red is cold molecular hydrogen gas, two hydrogen atoms bonded together. 

The MIRI image looks at longer wavelengths, and it’s also brain-fryingly amazing:

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