

Computing planetary positions – a tutorial with worked examples (2003) - catilac
http://www.stjarnhimlen.se/comp/tutorial.html

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sizzzzlerz
If you're interested in this type of computation and have some basic knowledge
of Python, there is a package called pyephem that you can install that allows
you to perform all sorts of calculations on the planets and other astronomical
bodies. It uses the same ephemerides data set that is used by professional
astronomers so it is quite accurate.

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vamin
PyKEP ([https://esa.github.io/pykep/](https://esa.github.io/pykep/)) is also
quite good.

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yoha
Some of the links from
[http://www.stjarnhimlen.se/comp/ppcomp.html#22](http://www.stjarnhimlen.se/comp/ppcomp.html#22)
are dead. If you want human-readable physical and orbital data for:

* planets, go to [http://ssd.jpl.nasa.gov/?planet_phys_par](http://ssd.jpl.nasa.gov/?planet_phys_par) and [http://ssd.jpl.nasa.gov/?planet_pos](http://ssd.jpl.nasa.gov/?planet_pos) (it points you to a table [http://ssd.jpl.nasa.gov/txt/p_elem_t1.txt](http://ssd.jpl.nasa.gov/txt/p_elem_t1.txt) where elements need to be corrected for a given date, see [http://ssd.jpl.nasa.gov/txt/aprx_pos_planets.pdf](http://ssd.jpl.nasa.gov/txt/aprx_pos_planets.pdf))

* moons, go to [http://ssd.jpl.nasa.gov/?sat_phys_par](http://ssd.jpl.nasa.gov/?sat_phys_par) and [http://ssd.jpl.nasa.gov/?sat_elem](http://ssd.jpl.nasa.gov/?sat_elem)

* dwarf planets, asteroids, etc, go to [http://ssd.jpl.nasa.gov/sbdb.cgi](http://ssd.jpl.nasa.gov/sbdb.cgi)

Also, some more data here
[http://ssd.jpl.nasa.gov/?constants](http://ssd.jpl.nasa.gov/?constants). If
you want more precise orbital elements at a given epoch (they vary through the
year), use
[http://ssd.jpl.nasa.gov/?horizons](http://ssd.jpl.nasa.gov/?horizons) (using
the Telnet interface, first choose "Ephemerides" (e) and then "Elements" (e).

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McUsr
It is a great fun to compute Planetary positions. You should really read a
book named "Astronomical Algorithms" by Jean Meeus. That is the ultimate
source for those computations, for hobby use. (There is a really nice chapter
in there, about accuracy, and interpolation of values). You'll find various
implementations of the algorithms on the net.

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davidw
Apropos - does anyone have suggestions for good Android apps for things like
this? I'm looking for something pretty for my kids, that lets you look at some
different things, like how the moon goes around the earth, night and day on
the earth, seasons, and maybe some of the other planets too.

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bengali3
not sure about mobile, but I would think Kerbal Space Program has most of the
physics done, as well as an active mod community. I've always thought an
accurate solar system mod would be pretty cool

~~~
Lambdanaut
It exists. Check this out:
[http://forum.kerbalspaceprogram.com/threads/55145-0-90-Real-...](http://forum.kerbalspaceprogram.com/threads/55145-0-90-Real-
Solar-System-v8-5-Dec-23)

It's also a lot more difficult than the stock solar system.

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amelius
Does it show how to compute the error margins?

