Retrograde Motion

[Leena n Dominic]

could someone help me with the retrograde motion explanation of the planets Mars & Saturn. I am still unclear how the Earth's faster orbital movement makes the outward planets movement go back and forth (like a 'Z' shape movement)


http://antwrp.gsfc.nasa.gov/apod/ap070407.html


http://antwrp.gsfc.nasa.gov/apod/ap060422.html

[Chris Peterson]

could someone help me with the retrograde motion explanation of the planets Mars & Saturn. I am still unclear how the Earth's faster orbital movement makes the outward planets movement go back and forth (like a 'Z' shape movement)

Stand in a room with something between you and one of the walls. Move yourself in a little circle, a meter or so in diameter. Note how the nearby object shifts with respect to the more distant wall. That's exactly what you are seeing with retrograde (and prograde) motion. Depending on what direction you are moving, the object appears to be shifting one way or the other.

[Leena n Dominic]

ya... i also googled it and the diagrams helped me understand it more clearly

Thank You