# Understanding the JPL Ephemerides

I'm working on an animation that replicates our Solar System. I know this has been done before, but I'm working on something that requires me to make one myself. With that being said, I'm having a tough time deciphering the JPL Ephemerides. Particularly for the Moon because I have already figured out how to work the VSOP Ephemerides, which gives me the positions for the planets.

Does anyone know of a source I could use to learn how to utilize the ASCII JPL Epehemerides file that are found here? It would be a huge help and I think a step by step walk through would probably help others in the future.

Thanks!

There is a python package called Skyfield that loads, reads and interpolates the binary forms of the JPL Development Ephemerides or DEs for you, and does everything else you need to get the absolute best results possible from them. If you can use even a tiny bit of python then this would be the way to go rather than trying to figure out how to interpolate JPL's "special flavor" of Chebyshev polynomials.

See these in Space Exploration SE:

and also see how easy it is to do things like this with Skyfield in this answer to Sunset on [Mountain] from [Viewing Point]

Also this answer to How to calculate the planets and moons beyond Newtons's gravitational force? shows how I used JPL's Horizons interface output (which also interpolates the DEs using Spice) to compare my numerical orbit integrator results to the ephemerides.

And just for fun see How to pronounce “Ephemerides”? in English SE.

• @whathm Sorry, for some reason I missed your first comment. No, the bounty is totally independent of what you would like to choose to accept if you decide to accept anything at all. It's just for a new user who found a really interesting/useful link.
– uhoh
Jun 13, 2020 at 23:12
• @whathm as an aside, the Python package Skyfield is a complete solution, if you are pressed for time and it does what you need, it's an excellent solution.
– uhoh
Jun 13, 2020 at 23:14
• Ahh gotcha. I think I misunderstood how bounties work. You can assign it to any answer regardless of whether the question asker has chosen a solution. Is that correct?
– Jee
Jun 13, 2020 at 23:15
• Aaaand you just assigned it. Hahaha ok, I totally misunderstood them. Sorry about that.
– Jee
Jun 13, 2020 at 23:16
• @whathm no reason to be sorry at all! Comments are for clarification, and Stack Exchange is different than most other sites and takes a while getting used to.
– uhoh
Jun 13, 2020 at 23:17