For the sample"Solar-System 5",how to get X,Y of

well,the planets spin and spin,but I found self.earth.getX() 's value doesn’t change,so,how to get its position?Thanks for anwering this simple question.

The relative X position is always 0, in this case. You are looking for the absolute X value, meaning relative to render:

self.earth.getX(render)

You can also use setX(render, n) to set the absolute position.