What is retrograde planetary perihelion precession?

1. Jun 19, 2011

magheera

I know what each word mean independently, I'm just confused as to what sort of motion is trying to be described as a whole.

2. Jun 19, 2011

tiny-tim

hi magheera!

perihelion precession means that the perihelion moves slightly each orbit

usually, this is prograde, which means in the same direction as the orbit itself

retrograde means the perihelion moves in the opposite direction to the orbit

3. Jun 19, 2011

magheera

fantastic! Thanks so much.