Question

why plannet rorates each other

Answer 1

planets will rotate objects that have a higher gravity than them. An objects gravity is what allows it to have objects rotate around it

Answer 2

HOLA!!

HERE YOUR ANSWER IS

(IF IT IS LOGICAL APART FROM YOUR SCHOOL SUBJECTS.MOREOVER I'M JUST SAYING WHAT MY SENIORS TOLD ME)

There is a concept in space that all the celestial objects used to orbit other celestial bodies or get being orbited by other celestial body.This is why you could see orbiting.

HEYA ANOTHER THING I HAVE TAUGHT BY MY SENIOR

Black hole size can be calculated by the orbits in it.You may think that the word 'orbit' here may be crazy but actually you can replace sun by 1 solar mass of black hole.

HOPE ITS CORRECT