I've found an interesting article on adding radial gravity to box2d.
http://www.vellios.com/2010/06/06/box2d-and-radial-gravity-code/
To port this to lua though I need to calculate distance squared and normalize distance.
Love2d doesn't seem to have the functions to extract the appropriate vector, which is a shame.
Unless my math is lacking and somebody could help me out.
I can alway switch to box2d but love2d seemed like a neat solution.