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Node markers on Moon orbit line don't coincide with ecliptic guide - why? (Parallax Effect)

Originally from ticket #19407.

When displaying the lunar asc and desc nodes on the Moon's orbit path, they don't show up at the positions where the Moon's orbit line crosses the Ecliptic guide but are offset from those intersection points by several degrees.

I was wondering if there was an astronomical reason for this or if it was a bug. I considered that it might be due to lunar parallax but the effect is the same regardless of latitude.

Can you advise?

Submitted from:


To get a better idea of what we're talking about, can you upload a screenshot/screencast and/or a Starry Night File (File > Save...) ?

I'm going to have a look on my side too, but it'll help to see it from your perspective.

- Dave

Technical Director - Simulation Curriculum Corp.


Sure - here's a .snf file and a screenshot of the Moon at its node, with the ascending node marker several degrees off to the right along the orbit.



I believe this is a parallax effect. Set your location to the centre of the Earth and you'll notice that this goes away.

- Dave

Technical Director - Simulation Curriculum Corp.

Ah - yes, I hadn't considered setting location to earth centre. Thanks for clearing that up.





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