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This article got me thinking if kepler orbits explain how a planet moves in a solar system how can a planet migrate as explained in the article. At some point don't the kepler orbits must need some other model to explain their positioning?

"Jupiter would have moved right through the primordial asteroid belt, emptying it and then repopulating it with scrambled material from both the inner and outer solar system as Jupiter then reversed course and headed back towards the outer solar system," DeMeo and Carry write, stressing that further observations should nail down how faithfully this scenario represents reality.

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up vote 2 down vote accepted

Kepler orbits cannot explain planetary migration as they assume constant orbital parameters such as semi-major and -minor axes and constant eccentricity. To explain planetary migration you would need at least Newtonian mechanics and numerical models, i.e. you would need the concept of gravity and the means to calculate the effects of gravity.

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Kepler orbits apply only to 2-body systems.

They apply only, if the masses aren't too large and the orbits aren't too close. Otherwise relativistic effects occur, as for the Sun - Mercury system.

Kepler orbits only apply, if the bodies are sufficiently spherical.

As soon as a third body comes into play, the system can become chaotic.

Too many conditions, especially for our early solar system.

Strange orbits like those around Lagrangian points, or horseshoe orbits can occur. Orbital resonance can stabilize as well as destablize orbits.

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