1. The problem statement, all variables and given/known data Given the multipole moment of the mass distribution how would I go about determining that the multipole moment expansion is invariant. I 2. Relevant equations http://cohengroup.ccmr.cornell.edu/courses/phys3327/HW2/hw2.pdf 3. The attempt at a solution I need to explicitly show how the coordinates transform over an orthogonal rotation. I'm not sure how to do this part explicitly and for an expansion of any multipole term. The link to EX 2.2 is similiar to what I'm asking but instead of a translation I need to show for a rotation of the basis.