Recent studies have discovered that Jupiter’s seemingly colorful cloudscapes are likely caused by the local abundance of only a single haze molecule, called a chromophore, that is red in color. This is a relatively new discovery! Here, a JunoCam image of the Great Red Spot was scaled by the color difference to its deepest red, and then cut into transparent layers which overlap in regions where more chromophores are concentrated in the clouds.

Note that it’s common in spacecraft images to see green and blue colors within the clouds as well, but in discussions with experts I learned that those are areas of low cloud density where the color is a byproduct of the scattering of light in the atmosphere rather than reflecting the composition of the clouds themselves. The vast majority of images of Jupiter have these colors greatly enhanced, whereas the real planet looks very beige and brown to the naked eye.

I started with a JunoCam image of the Great Red Spot, which was processed by @_TheSeaning on twitter. It took me a while to figure out how to re-process it not by separating colors, but rather by how far from Red each pixel in the image was. This way the layers will show “amount of redness” by location. It’s like a grayscale, but instead of scaling to black and white it’s scaled to the color of the Great Red Spot.

Even with a lot of manual processing, the contours don’t come out very smoothly with this image processing technique. I made the first version using vellum paper which is very soft, so combined with the pixel-y data it made it a giant pain to cut.

Overall it came out pretty cool, but as suspected it does take quite a bit of backlight to actually see the layers. With less direct light it appears much more hazy and homogeneous. Perhaps it’s an interesting feature of the piece that reflects some reality– we do often have to enhance our images to see variation in cloud color. But it doesn’t make for much to look at. I even experimented with backlighting it using an LED tracing tablet, but ultimately just didn’t love how it came out.

Then someone on twitter gave the suggestion to try lighting gel material! These are perfect because they’re made to cover stage and photography lights to give them color, but still allowing high transmission of the light. I’d never interacted with it before so I didn’t realize how thin it is– perfect for cutting, though delicate so it still took a fair amount of work. What’s perfect about these is the sheets come in a specific color at some set percentage of transparency. So I used one layer of 75%, two of 25%, and 3 of 12.5%. The only downside I’ve found, other than being delicate, is that they are extremely SHINY, which combined with the plexi over top makes them very hard to take pictures of! But, I think it’s minor compared to the pop of color you get in this version– very happy with how it came out!

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