Are Planetary Orbits in the Solar System Flat or 3D?

[geoffleonard]

I was wondering, after reading a few posts on various things related to 'The clockworks of the solar system' such as angular velocity and orbital periods,in a 3-dimensional sense, are planets orbital paths all over, or are they flat on one plane, varying in only 2 dimensions?
i imagine it varies in the third dimension just as much but I'm not sure.
thank you everyone

 

[tiny-tim]

hi geoffleonard!

if the Earth was the only planet going round the Sun, with no moon, its orbit would be 2D

the presence of other planets, particularly Jupiter, disturbs the Earth's orbit very slightly into the third dimension, since the other planets are orbiting in different planes

however, this effect is extremely small, and insignificant compared with the effect of the Moon, whose orbit round the Earth is also in a different plane

(but over billions of years, Jupiter's effect on the Earth-Moon system may be enough make the orbit unstable … nobody knows)

 

[gneill]

Ignoring small perturbations, each planet orbits in a plane. These planes have small inclinations with respect to each other. The plane that the Earth orbits in is referred to as the ecliptic plane (so from our point of view here on Earth, the Sun travels in the ecliptic plane). All of the planets' planes are pretty close to the ecliptic plane (within a dew degrees of inclination). http://en.wikipedia.org/wiki/Inclination" .