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nuki

simulating celestial bodies

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Doing some shots of planet earth where I'd like to have plausible transformations for the sun, moon, earth (ideally including its axis wobble) and star-backdrop (rotation only) relative to each other. Since there's different models in respect to their origin and accuracy the matter is a bit confusing for me to untangle. Hence I was hoping someone here might have attempted something similar and could point me to a comprehensive resource.
In the end I'd like to have a float slider to adjust datetime driving an approximation of the mentioned celestial bodies' transformations.

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@nuki something like this --Celestial mechanics--I have Old File very Old

 

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sure - would be great if you're willing to share! in case you remember any resources you used that'd be helpful too.

fyi - just found this

Edited by nuki

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hey, thanks for your links! After some digging through what NASA has to offer I think I will either go with using their HORIZONS system (super accurate but I'd have to fetch and store a ton of data in a LUT) or the Keplerian approximation using the specified variables (continuous and I dont need to get into telnet).

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Posted (edited)

hey tesan, cool stuff! judging from the twitter it seems to be a gravity based simulation?

I've actually spent a few weeks on this and implemented the approximation formula nasa provided so generously. Also extended it by transformations into ecliptic/equatorial/geostationary coords, axial rotation and satellites. Evaluating its accuracy probably took longer than writing all of it, also because it was more fun ^^. You can watch events like eg. the transit of mercury on 01/11/1605, a mars close approach 13/07/2065, solar ecplises, regressions....most stuff is accurate to within one degree (in 3000bc-3000ad), although the moon is more like 1.5 (didnt do any of its perturbations - yet).

Here's some screenshots - will update this post as soon as I get around publishing it. my workstation decided to die and is holding the latest version hostage atm...

sosy.thumb.jpg.996b4c29b781cb547bb29a3099c717cd.jpg
note: for the visualization I had to flatten pscale and P a bit - the real dimensions are quite insane (eg. earth, moon and iss would appear to be a single dot). The sim is in AU with 64 bit P and time, so internally everything is calculated properly.

Edited by nuki

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In the Files you can Download everything , He provide the File and on The NASA you have Data or other resource
 

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Posted (edited)

thats cool, didnt see the files! he's using the HORIZONS system, which is very accurate but needs data to be cached and interpolated, or fetched over the internet (which may cause issues on a farm). I implemented the less accurate, continuous offline version with the keplerian formulae. Was very interesting diving into this - looking up to the stars at night has become a lot more exciting to me for sure!

Btw, for the stars there's a neat recent post on Erwan Leroy's blog!

Edited by nuki
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