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A bit of background, I'm currently making a 2d graphical representation of the planets orbits around the sun with Python for a university project which currently looks like the picture below (not including Neptune for an easier to see picture).

The simulation starts with the planets all at their perihelion all on the same y-axis. I'm quite certain that the planets perihelion's don't neatly line up like this and was curious where each planets perihelion/aphelion are relative to the sun in this 2d representation.

I did try searching although I wasn't 100% sure what to search or if this is an easily googleable question.

Everything is to scale in this simulation. I'm doing calculations of Newton's Law of Universal Gravitation using real values for the planets distances, sizes etc so would like this to be as accurate as possible. Currently, the effect of the planets lining up like this does affect the simulation very very slightly and I'd like to make it as accurate as possible for my own sake.

The aim of this work is to demonstrate Kepler's laws which I plan to include initially by drawing ellipses to display the planets orbits which will clearly look strange if they all have the same perihelion/aphelion locations.

Any help/feedback appreciated.

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Of the six orbital elements astronomers usually use to denote orbits, the two you need to use are the argument of periapsis $\omega$ together with the longitude of the ascending node $\Omega$. If we set the x-axis as zero longitude, then the perihelion is at angle $\Omega + \omega$ (in a 2D flat solar system; in 3D reality inclinations shift things a little bit).

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  • $\begingroup$ Thanks, this is exactly what I was looking for. $\endgroup$
    – rhyso98
    Commented May 11, 2021 at 21:32
  • $\begingroup$ @rhyso98 One of the external links on that Wikipedia Orbital Elements page is to The JPL HORIZONS online ephemeris. You can use Horizons to obtain orbital elements, as well as actual positions of Solar System bodies. $\endgroup$
    – PM 2Ring
    Commented May 12, 2021 at 1:18
  • $\begingroup$ Eg, This link uses the CGI interface to get orbital element data of Jupiter on 2000-1-1 at 00:00 & 12:00 TDB. You can get the same thing via the Web GUI $\endgroup$
    – PM 2Ring
    Commented May 12, 2021 at 1:30
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    $\begingroup$ @PM2Ring wow this is an excellent resource I appreciate it. I was struggling to find the orbital elements for the planets but this is perfect thank you. $\endgroup$
    – rhyso98
    Commented May 12, 2021 at 14:52
  • $\begingroup$ @rhyso98 No worries. There's a bit of a learning curve to Horizons, and I'm certainly no expert on it, but I'm gradually learning my way around. ;) I see that you do some Python coding. At the end of this answer there's a link to a Sage / Python script that fetches data from Horizons. $\endgroup$
    – PM 2Ring
    Commented May 12, 2021 at 15:09

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