So here's a sketch of an idea i had for something i've been wanting to try in maya for quite some time but never knew if it was something i'd be able to do (without spending an eternity forum/tut hopping in hopes of finding the answers) and i think after i do a bit more research i'll be able to do something like it. The idea is to call for particles to either be emitted from the sphere center or at any random location within the sphere and have a mild velocity going outward. Place a cube somewhere in the sphere and record the location of its 8 vertices. Then, use the "position" of each particle to write an If/THEN expression that basically states: IF a particle's location is within these vecotrs (x,y,z locations) then it's color will change to a random value between white (what all the particles are by default) and blue.
I've learned a bit about writing expression in the past few days, but i haven't learned about conditional statements/test/whatnot yet...so i'll see if i can't figure out an expression for this and give it a go. If anything, i might just be able to use dynamics and state that whenever a particle comes in contact with the cube (which obviously wouldn't be rendered) it'll change to a random color within a given range...so either way i'm sure i'll come up with a technique to make this idea happen.