I was experimenting with various star system designs with a gravity simulator, and one of the patterns I ended up with is best described as a planet with a very elongated elliptic orbit that itself rotates around an axis located at/near one of the orbit's foci. This gif illustrates it pretty accurately:


I believe I created this by simulating a low-mass body moving near the large-mass body and falling into orbit, but at a slight angle so as to create an offset that shifted the orbit every revolution. Would this be possible with an actual planet and a star? If so, would there be any noteworthy side effects aside from the obvious (e.g. having extremely varying climates at different points during the year)?


Not only is this possible, it happens with real planets including the Earth. It is called Apsidal precession. This cycle and a similar cycle relating to the Earth's axis Axial precession are known as the Milankovitch cycles. They are believed to be a factor in long-term climate changes including ice ages, though how significant they are is not well understood. If a planet had a large eccentricity (like Mercury or, taken to an extreme, your example), the effects of that would dwarf the effects from the precessions and likely make the planet uninhabitable.

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    $\begingroup$ Here is a Khan Academy video discussing these topics (I couldn't put it in my answer because I am restricted to 2 links). $\endgroup$ – Tom Anderson Feb 26 '15 at 5:56
  • $\begingroup$ It depends how far, and for how long the planet is out of the habitable zone. Place it around a star with a wide habitable zone, and perhaps it might be okay. $\endgroup$ – user3082 Feb 26 '15 at 7:56

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