As you probably know, the planets have pretty predictable orbits around the sun but what exactly causes the complex movement of celestial bodies in the sky from Earth's surface? Mars is an excellent example of this.

Mars example

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    $\begingroup$ It is unclear what you are asking $\endgroup$ – Conrad Turner Jun 4 '16 at 2:46
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    $\begingroup$ The planets orbits are actually quite predictable. It just took many centuries and improvements in equipment and telescopes before they were figured out. Is this what you're referring to? youtube.com/watch?v=kbynKfNfHk4 Youtube links aren't recommended for questions but in your case, your question needs more clarity. $\endgroup$ – userLTK Jun 4 '16 at 3:51

The apparent motion of planets is complex but predictable.

The apparent motion is due to the combination of three different motions:

  • The rotation of the Earth,
  • the motion of the Earth around the Sun,
  • and the motion of the planet around the Sun.

The Planets move in ellipses, slightly perturbed by other planets.

These motions are predictable, and their combination is straightforward trigonometry. The resultant motion is complex, the planets appear to loop relative to the stars, but entirely predictable. We know exactly where the planets will be in the sky for any time for many thousands of years in the future or the past.

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    $\begingroup$ Small point to add cause it's often overlooked but inclination too. It was only after Kepler worked out that orbital inclinations were constant, always with the sun in the center, that he was able to do away with orbital oscillations and work out his famous laws. His estimated Mars was 1 degree 50 minutes (1.833 degrees), which was impressively accurate. Currently listed at 1.851 degrees inclination to Earth. Source below. $\endgroup$ – userLTK Jun 4 '16 at 17:10
  • $\begingroup$ books.google.com/… $\endgroup$ – userLTK Jun 4 '16 at 17:11

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