From the Vault: Jupiter and the Galilean Moons

In the From the Vault series, I feature an older image which hasn’t been seen here before and I talk about the capture and processing and hopefully highlight why this image is special to me.

The feature image in From the Vault this week is a portrait of Jupiter and the Galilean Moons, the Jovian system in high resolution. Captured on May 11th 2007, this was one of my most ambitious projects of that year, and took hours to capture and many many more hours in processing. It shows Jupiter with her 4 Galilean moons, Europa, Callisto, Ganymede and Io all at the same scale, in their correct positions at the time of capture.

It’s a good time for this image to be featured again, in the International Year of Astronomy – 400 years since Galileo first used a telescope to observe Jupiter’s Moons.

Jupiter and the Galilean Moons (click for full size)

Jupiter and the Galilean Moons (click for full size)

I took 6 images to create an animation, showing the rotation of Jupiter and the dance of Jupiter’s Moons as they orbit the gas giant. Please continue reading to read more about this image, and to see the animation.

The animation of the Galilean Moon Dance was constructed from 6 frames and is presented in a sweep back and forth style. The moons from right to left, show Europa and Callisto moving to the left having recently passed in front of Jupiter, and Ganymede is on the right moving towards Jupiter for a transit event. Io is behind the plane of Jupiter moving to the right. You can see the animation by clicking on the following link:

—> Jupiter and the Galilean Moon Dance <— (700k animated gif)

Remember to expand the window if your browser resizes it.

Detail (albedo features) was captured on both Ganymede and Callisto, which still amazes me sometimes – that amateurs can capture markings on a ~2600km wide moon that’s 650 million kilometres away! The image below shows a comparison of the moon images captured that night, with a simulation courtesy of NASA’s Solar System Simulator.

Callisto and Ganymede

Callisto and Ganymede

The image and animation remains a favourite of mine just because of the amount of work that went into it during capture and of course the days of processing afterwards. It’s not often that you see the entire Jovian system in high-resolution, all at the same scale, at their correct positions, and especially in motion.

The image has been publised a number of times in astronomy magazines, including Astronomy and Australian Sky & Telescope.

Now onto some details about capture and processing..

Due to the small field of view of the 640×480 pixel resolution DMK21AU04, I couldn’t capture the whole scene at once. I had to divide the system into 4 areas which had sufficient overlap that I was able to construct the composite showing the moons at their correct position at the time of capture.

The image below shows the relative fields of view that were captured.

Demonstration of the 4 capture areas to cover the whole system

Demonstration of the 4 capture areas to cover the whole system

The data was captured with my normal Planetary Imaging Equipment, except that in 2007 I was still using the firewire version of the DMK – that is, the DMK21AF04 instead of the USB DMK21AU04 which I use now.

I recorded at 30fps, 1/30s exposure and gain was at maximum. For Jupiter, I captured for approx 40 seconds each channel, and for the moons I captured for approx 45 seconds in each channel. By the time I did this for each of the 4 fields of view, there was about 10-15 minutes between each frame in the animation.

Processing was also fairly standard, using my normal planetary image processing routine with approximately 500 frames from each channel stacked for Jupiter, and about 100 frames from each channel for the moons. The moons were processed completely seperately and were combined into the composite using Photoshop.

Raw frames from each of the 4 areas of capture were used to ensure correct alignment of the moons when the composite was made.

If you love this image as much as I do, it’s available to purchase as a greeting card, matted print, canvas or framed print at RedBubble.

Thanks for reading and thanks for allowing me to share with you.

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