The Tarantula Zone. Credit: Robert Gendler, Roberto Colombari,
Hubble Tarantula Treasure, ESO, JWST, amateur sources
I should have commented on this picture yesterday, but I didn't, because my sense of color was thrown off by it. Why is the Tarantula Nebula yellow? It could be that this picture is strongly bringing out the cyan-green OIII emission that is most certainly present in the Tarantula, and combined with the red color of hydrogen alpha that is most
definitely present, the overall color may be yellow.
And, okay. I googled "Tarantula Nebula" and "pictures", and I got a lot of yellow-looking Tarantulas. Well, confession: I don't much like yellow color in emission nebulas, and if they are made to look yellow, I want an explanation for it.
Okay. One of the sources that Robert Gendler apparently used for his picture was an ESO image, and I think it was this one:
The Tarantula Nebula. Credit: ESO/IDA/Danish 1.5 m/R. Gendler, C. C. Thöne,
C. Féron, and J.-E. Ovaldsen
As you can see, the ESO image (where Robert Gendler was also involved) shows the Tarantula Nebula in the same shades of yellow as in the APOD, with some patches of rusty reddish and others of yellowish green. What I find most strange about it is that the
ESO page tells us that this is an RVB image, essentially an RGB image. That would mean that the picture shows us what the Tarantula Nebula would look like to our eyes, if our eyes were many, many, many times more color-sensitive than they are. I don't believe that the Tarantula would look like that, if we could see its colors. Compare the ESO image with this RGB image by David Malin:
David Malin's picture is quite old and somewhat lacking in resolution, but he was always very careful with his colors. He created his RGB images from the strength of the signals through his RGB filters, (actually, glass plates). So, if he got a strong signal through his red glass plate but weak signals through his green and blue glass plates, then he would show us a red object. And as you can see, his Tarantula nebula looks very red or reddish pink. The center is overexposed, both due to the brightness of the nebula, but also because appreciable amounts of green OIII are present there.
So while I can admire the details and resolution of both the ESO image and today's APOD, I still believe that David Malin's picture shows us what the Tarantula Nebula "really" looks like. Or what it would look like to our eyes, if we could see it in color.
You may or may not agree with me. But here, I'm being the stubborn Color Commentator.
Let me end by saying that Robert Gendler is a fantastic astrophotographer who is amazing at processing images. Many of his pictures are absolutely stunning. Just take a look at this picture of galaxy M106, where all the colors are "present and correct" and absolutely gorgeous-looking (and yes, the yellow hues here couldn't be more perfect and true):
That's stunning, Robert! You know I have the greatest admiration for you. It's just that you and I don't agree on the Tarantula Nebula.
Ann