Source 30

http://zebu.uoregon.edu/~imamura/121/lecture-2/planet.html

• The motions of the planets are roughly confined to the ecliptic. This implies that the orbits of the planets are roughly co-planar with the orbit of the Earth about the Sun.
• Not as obvious is the fact that all planets orbit the Sun in the same sense as does the Earth. This means that they usually move in the west-to-east direction on the Celestial Sphere (CCW as viewed from the NCP). However, an exception to this motion is the retrograde motion sometimes exhibited by the planets.
• The planets' orbits are all roughly circular in shape.