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Headshot of Emily Lakdawalla

JunoCam "Marble Movie" data available

Posted by Emily Lakdawalla

22-08-2016 16:56 CDT

Topics: pretty pictures, amateur image processing, Juno, Jupiter

Since a few days after entering orbit, JunoCam has been taking photos of Jupiter every fifteen minutes, accumulating a trove of data that can be assembled into a movie of the planet. This first orbit of Jupiter was a very long one, taking Juno more than 10 million kilometers away. Because JunoCam is a wide-angle camera, Jupiter appears tiny from such a great distance. Fortunately, Jupiter is colorful enough that it's not featureless, even when it appears so small; you can see its red belts and occasionally the red spot show up in the photos. The JunoCam team is calling the movie taken from this first long orbit the "Marble Movie," because that's what Jupiter looks like, a little rolling marble.

The JunoCam team has released the first month's worth of Marble Movie data in two large chunks. Space imaging enthusiast Gerald Eichstädt has developed an automated routine to process those chunks of data, producing thumbnails, which means I can now post one of my browse indexes to all the data.

Jupiter doesn't look too impressive in these pictures; the best thing to do is to animate them. Gerald is working on just such an animation. Below is a preliminary version of his work with the data, covering the period up to August 11 (the most recent data currently available). In this movie he's aligned all the color channels and has emphasized the moons, but he hasn't yet taught his algorithm how to handle the appearance of the moons as they cross the disk of Jupiter. The moons are only barely detected by JunoCam and are (in the original data) less than a pixel across; at times they appear to wink out or twinkle because they weren't bright enough in some frames to be detected by Gerald's algorithm. They may also disappear where they pass into Jupiter's shadow.

A couple of other peculiarities about the data: Initially, they alternated blue-filter and RGB images as they took one photo every 15 minutes, so the frames of this animation are spaced half an hour apart (since Gerald used only the RGB frames). Then they went through a period where it was just RGB every 15 minutes, which means Jupiter's rotation appears to slow down. Finally, there was a period alternating methane-filter and RGB images, so the rotation speeds up again. There were two gaps in the data on July 14, making for a couple of little jumps in the animation. As always, watch for transits of moon shadows and moons themselves across Jupiter's disk. If you watch closely, you'll see Ganymede transit the disk at the same time that Io's shadow does!

These are sort of cool to play with but the real fun is going to come after this weekend. Juno is now picking up speed as it approaches for its first close approach to Jupiter since entering orbit. Perijove 1, as the mission calls it, will happen on August 27. All the science instruments will be taking their very first close-up data on Jupiter. I can't wait to see JunoCam's close-up images! In the meantime, check out my Marble Movie data browse page and stay tuned to the JunoCam website for the latest pictures.

See other posts from August 2016


Or read more blog entries about: pretty pictures, amateur image processing, Juno, Jupiter


sepiae: 08/22/2016 09:33 CDT

Marbelous! The 3 are Ganymede, Callisto & Io? Europa not visible? Been watching this 4 times now... Thanks for posting

sepiae: 08/22/2016 09:40 CDT

p.s. ... or is it an albedo-question? Europa isn't *that* much smaller than Io, and she should reflect a little better than her, no? I'm afraid I wouldn't be able to tell from positions here :)

LocalFluff: 08/23/2016 07:26 CDT

Galileo would've dropped his eye glass if he had seen this.

usafa43tsolo: 08/23/2016 10:22 CDT

I've been trying to figure out why the perspective between the camera and Jupiter doesn't appear to be changing. Over this period of time, I would normally expect the perspective would shift as Juno goes through it's orbit. Was that processed out or is there something else I'm missing?

LocalFluff: 08/23/2016 02:34 CDT

usafa43tsolo The perspective does change. It moves from the south and ends in the plane of the moons. The fastest moon Io has a period of about 42 hours.

Gerald: 08/23/2016 04:38 CDT

@sepiae It's Callisto, the outermost of the Galileans, which is barely visible in the animation. In the original fully resolved AVI one can see it twinkle in some part of the animation. It's very close to the background noise level, and is filtered out in several of the still frames by the preliminary and somewhat crude version of the noise filter I've used for this preliminary version. I hope, that I'll be able to resolve this issue together with the dimming of the moons near Jupiter.

sepiae: 08/24/2016 04:56 CDT

@Gerald: Aaallright, yes, thanks for the explanation :) Excellent job, thank you for this!

usafa43tsolo: 08/24/2016 10:46 CDT

@LocalFluff, you're absolutely right. On a larger screen (read: not my iPhone) and skipping from the beginning to the end, I can definitely see the perspective change. I thought it would have covered more of the orbit, so I was looking for a more drastic perspective shift. Thanks!

citius1974: 08/27/2016 11:44 CDT

Fantastic...Thank you for sharing this. Had to watch this one several times. I the individual frames (thumbnails) of pictures you posted (here:, I noticed a very interesting flash (I assume one of the moons) on the 13th image in on the 2nd to bottom row of pics. ANyhow, just great to watch this! - Carl (Michigan)

citius1974: 08/28/2016 10:22 CDT

I was able to find the specific frame I found so interesting: Frame 5583 (found here: Thanks again for posting this beautiful data and pieced together movie. - Carl (Michigan)

Gerald: 08/29/2016 10:01 CDT

@citius1974: Well spotted! The image shows a shadow on Jupiter close to the terminator, cast by one of Jupiter's moons:

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