# Elliptical Orbits and Resonance of Eccentricities

1. Jan 5, 2014

### Ian J.

Hi,

Dumb Question #1251:

What I understand so far (which maybe incomplete or wrong): in any system with multiple objects orbiting a larger body (either star+planets or planet+moons) each body can have an influence on the others, such that large bodies such as stars and big gas giants have a common barycenter for their elliptical orbits (e.g. Sun - Jupiter), and that there can be resonance in the orbits such that the orbital periods are related (2:1; 3:2; 5:1; etc).

What I want to know is:

1. How much of an effect does the eccentricity of any one body's orbit affect the eccentricity of the other bodies' orbits, significantly or insignificantly?

2. In the evolution of a system, does any resonance for the eccentricities of the orbits settle down to an observable pattern (similar to the resonance of the orbit periods)?

TIA

Ian

2. Jan 6, 2014

### tfr000

Any body that is significantly different in eccentricity from all the others will tend to end up unhappy - flung out of the system or into a new orbit. This is why the Solar System features mostly near-circular orbits. Objects in random elliptical orbits would keep interacting until they settled down into something similar. Even if the major axes of all the ellipses were in one exact line, they would soon be scattered by mutual interactions.

As far as how much each object affects the others, hard to say without specifying exact circumstances - and then you are getting deep into celestial mechanics.

3. Jan 6, 2014

### Ian J.

:thumbs: Thanks for that, that's actually quite a reassuring answer

4. Jan 7, 2014

### Devils

I'm happy with that answer. How do you explain that most orbits in the solar system are in the same plane, is it a similar argument?

5. Jan 8, 2014

### Bandersnatch

It's got more to do with the way the cloud of gas that ended up as our Solar System collapsed. By the time planets started to form, most of the material was already orbiting close to a single plane(the protoplanetary disc).