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I'm trying to grasp what a 2D "side-view" of the solar system looks like. There are many examples of a "top-down" view of the solar system. But the side-view confuses me somewhat.

The plane of reference is the ecliptic as far as I can understand and the earth's path viewed from the side follows this line exactly as the "orbital inclination" with the ecliptic is 0 degrees (see blue line on ecliptic plane in screenshot below).

Now for the other planets: Mars has an orbital inclination of 1.85 degrees, BUT when I use the Keplerian elements from JPL, it seems the plane is not only inclined at 1.85 degrees, but also tilted? See screenshot. I was expecting a perfectly flat line for the ellipse of Mars (like the one for earth). You can see that Mercury and Venus have the same problem.

Does this visualization make sense or am I doing this wrong?

enter image description here

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sloesp
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    "the plane is not only inclined at 1.85 degrees, but also tilted" I don't understand: don't "inclined" and "tilted" mean the same thing? – David Richerby Mar 20 '17 at 13:52

1 Answers1

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Your plot looks correct. The behavior you are experiencing stems from the different longitude of the ascending node of the different planets (the angle between a principal direction and the point where they cross the ecliptic plane). If they all crossed the ecliptic plane at the same node you will see the behavior you expected (lines at different inclinations).

In the following example I adjusted the view to make Earth (blue orbit) appear as a line. Other planets (Mercury, Venus, and Mars) appear as long ellipses.

Earth

If I adjust the plot to make Mars appear as a line, now the Earth pops out.

Mars

Even more dramatically if I adjust for Mercury:

Mercury

Escualo
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  • That is brilliant Escualo. The visualizations that you've added are very helpful too! Especially how you plot from the perspective of Mars and Mercury. So it's the "longitude of the ascending node" I need to read up on. Thanks a million! – sloesp Mar 20 '17 at 00:29
  • I recommend you buy the book "Fundamentals of Astrodynamics" by Roger Bate, Donald Mueller, and Jerry White. It is between $7 and $18 USD depending on whether you buy it used or new. It is a very gentle introduction to most aspects of classical astrodynamics, including orbital elements. – Escualo Mar 20 '17 at 00:53
  • @sloesp: If you imagine drawing a circle on a piece of paper and holding the paper flat in front of your eyes that would represent the earth's orbit. Mars' orbit is tilted 1.85 degrees. If you tilt the paper 1.85 degrees around the line from your eyes to the paper the circle will still look like a line. If you tilt the paper 1.85 degrees around a line across your vision you will see a narrow ellipse. That is what these pretty pictures are showing. – Ross Millikan Mar 20 '17 at 15:22