Our solar system is home to the Sun, eight planets, and tons of moons, asteroids, and comets. This January, I was able to image four of these planets: Mars, Jupiter, Uranus, and Neptune, as well as some of their moons. The following is an overview of my process and the final results.
(Disclaimer: I wanted to find a way to display all of the images taken and edited in one image, so I used Procreate to stitch five different images together. Although I only imaged Mars, Jupiter, Uranus, and Neptune for this post, I had previously taken a black and white picture of Saturn. I artificially colored and added it to the image to show the outer five planets of the solar system. This is not to scale or color accurate.)
Stacks on Stacks on Stacks
The aligning and stacking process for all four planets was virtually the same. Using Afterglow, I processed once planet at a time. I loaded all images from the observation into my workspace and turned on the sync orientation (using pixels) and sync display settings. This made it easier to work with all of the different images at the same time.
To start the aligning process, I used the Source Catalog with centroid clicks and planet centroiding enabled to select the planet in each of the images. Then, I merged all of the sources. This let me use the Aligner tool to align all of the images using the "Sources - manual" mode. I disabled rotation, scale, and skew to give the software less flexibility in aligning, allowing for a clean and accurate alignment.
Next, I stacked all of the images taken with the same filters using the with the "Propagate Mask" tool turned on. Once I had three different stacks for each filter, I matched the color map to the filter and then grouped the stacks together. I repeated this with each planet, and with that, the processing is done and I am left with a single color image!
Mars
My group mate Andreas Buzan submitted an observation for Mars on January 22nd. He took a total of thirty images; ten 0.3 second exposures with the Halpha filter, ten 1.2 second exposures with the U filter, and ten 0.6 second exposures with the OIII filter. I loaded all thirty images into Afterglow and used the general procedure outlined above.
Additionally, I used the histogram fitting tool and the photometric calibration tool to calibrate the zero points and white balance. Then, I selected the Halpha layer as my reference layer. This ensured that my image of Mars would have an accurate color. I used the mid tone stretch mode and made slight adjustments in the display settings to bring out as many features as I could. The iron in the dust on Mars reacts with the oxygen, creating an iron oxide. This is called Haematite and is what gives Mars its red color. Aside from the beautiful red color of the planet, you can also see Mars' ice caps! In this image, they appear slightly blue on each pole of the planet.
Jupiter
For this Jupiter observation, I used PROMPT-5 to take ten 1.5 second exposures with the U filter, ten 1.0 second exposures with the OIII filter, and ten 1.0 second exposures with the Halpha filter. Once returned, I used Afterglow to process my exposures using the same general procedure as before.
Jupiter was fairly straight forward to edit. In the Afterglow display settings, I used the midtone stretch mode to bring out the most detail and color without making the image look too over processed. I downloaded the image and used a general editing tool to make some final touches.
In the image, redish orange, yellow, white, and brown stripes are clearly visible. If you look closely, you can also see Jupiter's Great Red Spot, a huge 340 year storm on the surface! While the colors in the image are clear, their causes are still widely argued. The color of the white zones come from frozen ammonia crystals in the clouds. The redish orange and brown belts come from clouds at a lower altitude than the white ones. These clouds are thought to be made up of ammonia-sulfur compounds such as ammonium polysulfide. The Great Red Spot is often attributed to red phosphorus or another sulfur compound.
Jupiter's Moons
By decreasing the midtone level, I was able to bring out three of Jupiter's moons: Io, Europa, and Ganymede. I also adjusted the background level to reduce the skyglow coming from Jupiter. Io is more of a yellow color, whereas Europa and Ganymede appear more white. This is because Io is rocky and volcanic, while Europa and Ganymede are covered in ice.
Uranus
One of my other group mates, Ruby McGhee, submitted the Uranus observation. She used PROMPT-5 to take thirty 2.5 second exposures with the B filter, thirty 1.0 second exposures with the R filter, and thirty 1.0 second exposures with the V filter. I loaded the ninety images into Afterglow and followed the procedure to align and stack them.
Additionally, I used the WCS Calibration tool and Platesolve mode to extract sources from each stack. This adds a coordinate system to the image and allowed me to correct the color of the image with better accuracy. I then used histogram fitting and photometric calibration to calibrate the colors. I selected the B filter layer as my reference layer and made some final tweaks with the display settings to get my final image.
Methane gas on Uranus absorbs the red light when sunlight is reflected back out into space. This results in a greenish blue color.
Uranus' Moons
I lowered the mid tone level of my image and several of Uranus' moons became visible. I used Stellarium see what Uranus (and its moons) looked like at the instance this image was taken. This allowed me to identify each of them. Out of twenty seven moons, I was able to identify four: Oberon, Umbriel, Ariel, and Titania.
Neptune
At the time that these observations were submitted, it was difficult to observe Neptune because of the alignment and phase of the moon. Luckily, Dr. Reichart had been able to get some Neptune data for this activity. I uploaded all of his observation images into Afterglow and followed the same general procedure as before and color calibration process as I did for Uranus. This resulted in an accurate color image.
Like Uranus, the blue color is created by the methane in Neptune's atmosphere. Compared to Uranus, Neptune appears to be more green and pigmented than Uranus. In reality, Neptune is more green and Uranus is actually the more blue planet. However, both are equally as fascinating!
Neptune's Moons
I once again lowered the midtone level and using Stellarium, I was able to identify one of the moons. This moon, Triton, is the by far the largest of Neptune's moons.
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