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Let's say we're mapping Callisto's northern celestial hemisphere in a way similar to this map of Earth's.

Along with the stars (which let's just ignore for this question), this map will identify the paths of four objects:

  1. The Sun
  2. Jupiter
  3. Ganymede (closer to Jupiter)
  4. Himalia (farther from Jupiter)

Where on the map would these objects' paths be? Or at least how would I find the exact answers with math/software/etc.?

My assumptions/guesses:

  • Jupiter's path is relatively similar to the ecliptic but Callisto's orbital inclination or maybe Jupiter's might separate the two
  • Jupiter's moons are within a similar orbital plane to Callisto and would follow near Jupiter's path
  • the distance Callisto travels away from the sun in its own orbit is insignificant in determining the shape of the ecliptic

I have no idea if the axial tilt of Callisto or Jupiter would affect anything but it probably does.

If it helps, I've made this incredibly stylish and oh-so-fabulous template in case anyone wants to sketch it in Paint or something. The black dot at the center is the celestial north pole.

enter image description here

Thank you for your time!

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  • $\begingroup$ Obviously nobody here will fill that in for your. At best, someone might be able to point you towards the way to do it yourself, in which case, it would be good to know the tools at your disposal. Do you have access/can you use Matlab, python, etc.? $\endgroup$ – zephyr Jan 13 '17 at 14:43
  • $\begingroup$ I have access to Matlab. $\endgroup$ – Minok Samshin Jan 13 '17 at 18:38
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I'm not sure this answers your question, but I used Stellarium (free) to generate this image from Callisto's north pole (so its celestial north pole, in Draco, is overhead) with orbit trails turned on:

enter image description here

Unfortunately, the image is not only messy, but may be inaccurate, since Stellarium doesn't do a great job of plotting orbits long-term: Stellarium 0.10.4: planet orbits change over time?

So, I wrote https://github.com/barrycarter/bcapps/blob/master/ASTRO/STELLARIUM/callisto.ssc to create a video of the view from Callisto's north pole, but the results are fairly uninteresting: https://youtu.be/O2GHJM54uhQ and come with several caveats:

  • I assumed that Stellarium is accurate, not just in where it displays the planet, but also in how it determines Callisto's rotational orientation, and any other details required to depict Callisto's celestial northern hemisphere.

  • The video is in "starchart mode", which means the stars don't move. In reality, the stars would make a complete rotation about every 16.69 days. More specifically, in the video, Jupiter moves through the constellations. In reality, Jupiter would remain fixed (Callisto is tidally locked), and the constellations would move.

  • The one year (+ about 2 months) period I chose is not "representative" and does not repeat. There may be quite a few more interesting things happening after the period the video represents. In particular, note that the Sun takes about 12 years (Jupiter's orbital period) to travel Callisto's ecliptic, and only a fraction of that travel is show in the video.

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